The idea of Kira being a DLC only character might cause ire to some fans, or even just an oddity of why he isn't included. That is until you realize that Kira technically is in the game in the form of JoJolion's Josuke.
Lessened somewhat with the reveal of Kosaku, who is also Kira, who IS in the base game.
Dio treating his son well makes some sense when you think about it. He hated his dad's guts for being an abusive drunk, so he might strive to be a good father to his offspring in order to be less like him. Granted, this is Dio, so he'd probably show his concern in really...unusual ways.
Funny Valentine's Love Train can't block projectile GHAs. While we see both Gyro's Ball Breaker and Johnny's Super Spin breaking through the barrier in part 7, Kira and Caesar Zeppeli has no such excuse. Until you realize that Sheer Heart Attack counts as part of Killer Queen, not as a projectile, Bite The Dust entering the opponent's retina when he/she sees it, allowing it to bypass the barrier completely, and Caesar using the light reflected from both the bubbles ("Here's a new use for this!") and Love Train, trapping Funny Valentine. Hol Horse also uses the retina stunt via the Hanged Man, distracting Valentine long enough for a opening with the Emperor. The most glaring example is Mista's, where the only thing that allows Sex Pistols's bullets to break through Love Train is via raw sheer force
Iggy being later DLC and not part of the base game's initial roster references how he didn't actually join the good guys until well into Part 3.
Conversely, Fugo being DLC references how he doesn't stick with Passione at half point of Part 5.
Yoshikage Kira's Another One Bites The Dust rewinds time to where he needs it to be. While this is vastly inferior to both Dio's World and Diavolo's King Crimson, this allows Kira to rewind events where he is at a disavantage. While this may sound useless, Giorno Giovanna, Enrico Pucci, Kars, Both Jonathan Joestars and Funny Valentine use moves that gives them special ways to fight against their foes. One Bites the Dust later and not only Kira is healed, but the various characters have to regain their special ways.