That's a good observation. Fantastic Four needs to have a balance of darkness and comedy like the Guardians Of The Galaxy movies.
Yeah I don't think the Cold War sensibilities are necessarily going to be a leash on successful adapations of the FF. My mom is a fan of the original comics and having gone through them as a child I never got this sense out of them. And I'm sure it'll be the same for others. It's all in the execution, and of the ones that've come out none of them have really gone with the right approach.
Roger Corman was a B movie producer known for making movies on micro budgets and the entire project was instigated by an independent producer who held the rights to the franchise. Corman was also ultimately bought out after the film was released, meaning he made back all the money he'd spent, plus a profit.
A studio like Fox isn't gonna spend a mere million dollars that is not gonna cost them anything in the long run. They spent 125 million on the last one, after all.
In other F4 news:
Anybody play Marvel Heroes?
If anyone does, then get ready to kiss the Four (and the Silver Surfer) good bye.
It gets worse. Any costumes related to the F4, such as Future Foundation costumes, Bag-Man!Spider-Man, and so on are getting the boot.
"hence Doom being a wimpy American businessman and Galactus being a fucking cloud"
Maybe is just me...but I kinda like Galatus as cloud, it make him feel more like force that eat planet than this weird guy who eat because.....why he does again?
I mean, I never get a feel I should be scared by galatus, the only time I kinda like the chararter was in the cartoon and that was because of is voice actor sounding cool.
"My Name is Bolt, Bolt Crank and I dont care if you believe or not"

You need to get the right balance of not going too far in the realm of stupidity, while not downplaying the sense of fun and weirdness that made them work to begin with.