There is a trend of entertainers developing Lighter and Softer material after they reach the "mainstream," when their original stuff was much more adult-oriented, or, at least, "mature."
This is more obvious with rappers, who usually begin as anti-establishment and cynical musicians, and, as they go to Hollywood after they manage to get a hit out in the public's ears, begin to make more presentable appearances, going from "baggy pants and wifebeater" to "sport jacket and unbuttoned shirt" to "three piece suit." The only thing that doesn't change is the bling, it seems.
And it's not just the wardrobe that changes. A Saturday Night Live guest spot today, presenting an MTV Video Awards tomorrow, a little Sesame Street Cred, and before you know, they'll have a Reality Show about raising their kids.
The reasons for that are several. Either the entertainer actually changes his/her worldview after being exposed to a lifestyle until then unthinkable, he/she wants to try something new (like acting!), the Moral Guardians complained way too much about the song their kids insisted on listening to, or perhaps his pockets were lighter than he thought. But, the most common reason is having children - the entertainer doesn't want his kids to think of him as nothing more than the guy who shouted obscenities on TV, or he now feels how other parents felt about having his kids exposed to such obscenities.
Compare Tom Hanks Syndrome. Related to Scary Musician, Harmless Music and Bleached Underpants (when a work distances itself from its pornographic beginnings). So My Kids Can Watch happens when a performer does family-friendly fare with every intention of going back to business as usual afterwards.
The entire genre of hip hop as record companies discovered it and subverted it to broaden it to a larger audience instead of the inner cities. From "Rapper's Delight", "The Message", "Fuck the Police" and "Fight The Power", to ... whatever it is they do today.
Specifically individual rappers do it because either they are getting older and wealthier and thus some feel the subjects they dealt with doesn't relate as much anymore while others do it because they want to adopt an attitude of a "safe rapper", someone who can work with non hip hop artists and not scare off the latter's intended audience.
Jay-Z is a good example. He started his career with a drug-dealing background and a "don" persona. As he got older, wealthier and more famous, he obviously wasn't going to still deal drugs, so matured as a person, fully embraced the star lifestyle and it reflects in his music. He's no longer a gangsta because he doesn't need to be, and in a sense it's a natural evolution.
Sean "Diddy" Combs. Started as "Puff Daddy", a pot-loving rapper. Now, he owns a clothing line and. Sure, he was never actually Badass, but still, he went from advocating use of a illegal substance, to, well, whatever he is now.
Snoop Dogg. Went from rapper to violent movie star, then to comedy movie star (with a stopover in porn), and now has his own reality show about raising his kids. He even features regularly on Futurama, notably as the Supreme Justice of the world.
His music has also underwent a transformation, from hard-hitting thug anthems to more mellow "ladies' man" smoothness.
Gangstalicious: You know who my favorite rapper was when I was your age? Ice Cube.
Riley: That dude who does family movies? He was a gangsta rapper?
Ice Cube's last three albums pretty much re-established his street cred because of his return to form, especially the controversial song Gangsta Rap Made Me Do It. His music is still as raw as it was on his debut, And that's saying a lot. This trope only kicks in during his acting career..
Cube gave a rather sobering explanation for why he's taken family comedy films, saying it's the path of least resistance in Hollywood. According to him it hard to get serious dramatic black films funded, and that Hollywood prefer to finance black comedies instead.
Eminem — Began as a groundbreaking white rapper, achieved popularity with preteens, acted in a movie based on himself, now he records self-censored versions of his own hits (and he has put his daughter to sing in one of them, Squick).
Inversion (though not in the musical field): Will Smith, the Fresh Prince, another who was never badass, but went from actual rapper to gimmicky actor in his own sitcom, to serious actor. This was actually beneficial, and he has been nominated for two Oscars.
Eddie Murphy went from a famously profane and edgy comedian and actor in R-rated movies to a mainstream comedic actor who often appears in Disney and family films, with the occasional edgy film thrown in.
Bushwick Bill from Geto Boys (Jamaican born one-eyed dwarf, I couldn't make this up even if I wanted to), started violently in the early 90's. His new solo album is a gospel album.
Looptroop, Swedish anarchist rap group. Never really gangsta, but some change detectable. On their first album they had a song endorsing shoplifting; on the newest album, a cover of Bon Jovi's "Living On a Prayer"
Finnish rapper Steen1, first album was rather profanity filled anti-authoritarian rant, the second album more calm, (still zealous, though), on one single expresses remorse over glorifying a cop-killer on his first album.
Hardcore, alchoholic, Thug LOC from Aarhus Vest and part of the West-Coast inspired crew BANGERS is now part of "Selvmord" (Suicide), making Gangsta-gone-sensitive music with former Suspekt and Rune Rask (also all examples of this trope). Development... growing up... quitting alcoholism.
Jurassic Five often mocks this trope, rapping about staying true to rap. Or... something.
Inverted in the case of Michael Jackson, who became less "kid-friendly" as the time passed. Given that he started as a kid, that's probably natural.
Three Six Mafia is well on its way to being Rated G for Gangsta, seeing how their first album was about Satan Worship, and their latest includes a radio playlist hit.
I think their G-rating began when they won an Oscar—before Martin Scorsese, no less!note Immediately lampshaded by that year's host, Jon Stewart: "For those of you keeping score at home, that's Martin Scorsese 0, Three Six Mafia 1."
Ozzy Osbourne was known as a particular family-unfriendly rockstar with Satanic undertones and lurid legends of his backstage exploits. Since the airing of The Osbournes, however, he's viewed as a befuddled and doddering old man. His harmless media appearances since then include pitching World of Warcraft.
Epstein also required the group to shed their seamier Hamburg performance habits, such as drinking beer and smoking onstage, and cussing out the audience.
They may have been behaving better by the early 60s than they did in the fifties, but Ohhhhhhh boy did their subject matter in the late 60s reverse the trend... "Why Don't We Do It In the Road," anyone?
Word of God says that was intended as a comment on how humans have all these "horrendous problems" with the act of procreation while animals don't and will happily "do it in the road".
KRS One is a bit of a variation: one of the creators of Gangsta rapHardcore Hip Hop, he made one of the genre's defining albums with Criminally Minded, but went through a bit of a spiritual crisis after his friend and DJ Scott La rock was murdered. His music eventually became a lot less gangsta and a lot more Christian: he actually released an album called Spiritualy Minded.
KRS One is today a political black activist... Still gotta love the 10 classics on Criminal Minded.
Played straight and inverted multiple times by Nas. From Illmatic, to "Oochie Wally", to battling Jay-Z and declaring hip hop "dead", to signing with Def Jam and Fila shoe endorsements; all the while collaborating with the entire gamut of hip hop from DJ Premier and Pete Rock to Trackmasters and Puff Daddy.
And even non-hip-hop artists such as Korn and Damian Marley!
One of the many themes on Nas' 2012 album Life is Good is deconstruction of this trope.
When he came back to WWE in 2011 he still had to tone himself down a lot, since Monday Night Raw is TV-PG now. To his credit he at least tried to push the envelope a bit, as much as WWE would let him get away with anyway.
One film critic noted that Johnson started doing self-parodies of his "tough guy" action roles with films like The Tooth Fairy and The Other Guys before he had a solid status as an action star in the first place. That's right, he's doing self-parody of a version of himself that never existed.
John Cena is basically wrestling's version of this trope in effect. There was a time where he actually was rather profane, at least by wrestling's allowed standards. He himself chose to be more kid-friendly, just as WWE as a whole now is.
It's been rumored that at one time WWE considered making SmackDown live but UPN was terrified of giving Cena a live mic; this is the same man that later, live on Raw, tagged a limo with graffiti reading "JBL is poopy".
There's also the bit where Cena's also shoehorned into the role by the writers, who wouldn't allow him to drop to midcard and turn heel after he dropped his title the first time.
When this picture◊ surfaced of Metallica singer James Hetfield, a lot of people had this attitude. Metallica's confessional, tell-all documentary Some Kind of Monster didn't help much either.
Both played straight and averted by various members of the Wu-Tang Clan. Whereas Method Man has had an acting career including a Fox sitcom and a cameo in a Zach Braff movie, Raekwon, GZA, and others have stuck to simply making hardcore hip-hop.
Over in Britain we have Dizzee Rascal. He started out making grime, and now he makes much more poppy, lighter music.
Karen Mukupa. Oh God, Karen Mukupa. She started out in a hip hop/dancehall fusion duo with pot-smoking, anti-racist Natasja. Then Natasja died. Mukupa's music is now more down-to-earth and mainstream, and she devotes much of her time to writing kid's books about Africa and hosting reality shows.
Odd Future, arguably. They started out as something like rap's answer to GG Allin, gratuitously rapping about rape and breaking pretty much every social taboo you can think of just to piss people off and goad reactions out of sensitive listeners, but with their first group studio album The OF Tape Part 2 they shifted toward a more sensible form of Swag Rap with less lyrical (and musical) abrasiveness, albeit retaining their scatological sense of humor.