One thing I also so bright and shining, though it wasn't actually explored and it could have been, and the same has happened in the comics actually; a touch here and a touch there but not indepth into the fact that Charles Xavier is skeevy. Privileged, isolated, sheltered and skeevy. His causal all up in other people's minds in the show is only maybe on or two ethical rules away from his casual all up in other people's minds in other media.
Though in this movie, there were possible hints, for example, that for all he had 'promised' Raven, never to read her mind. It's likely he always was, whenever there was a roadblock and just wasn't telling her - instead coming across as insightful.
I always thought the person who ended up showing the most ethical concerns about telepathy was always JEAN, and that because she felt other peoples thoughts quite palpably as intrusions into HER space; and thus blocking them out for her privacy resulted in giving them privacy and giving her a particular perspective. Which is why I've always adored the relationship between Jean and Scott; the woman who can touch his mind with the man afraid of physical intimacy (for fear of hurting someone).
FirstClass did do one other thing for me though; in the past I've always tended to side with Magneto. But this time, I realized, he'd just as soon 'rise up', over currently oppressed peoples, as long as they were non-mutant. Wouldn't matter what else they'd been through as a people. And he (or the version that's based on First Class or branches forward and backwards through other media with similarities) would likely see anyone putting their own peoples ahead of mutants in general - as traitors. Never mind that Erik himself is drawing on the Shoah as his prediction for the future.
Like, when Erik's all 'Mutants First!'; what happens to non-mutant Jews? Yes? My personal head cannon Erik was not that oblivious in the slightest. But First Class Erik is, and made me realize that 1st Movieverse Erik was too. In X2? When he was messing about to end non-mutant life? Non-mutant Jews were dying left. right. center.
Not that Jews can't be oppressing (see anti Black riots in Israel right now). But still - lack of nuance. So much lack of nuance in the movieverse Eriks (both of them). And no one calling him on it at all.
At least Kitty Pryde once pointed out to him, that in his plans? Her Jewish parents would die and asked him how that was different than the Nazis. But y'know, that was wwaaaaaayyyy back in the mid-late 80's comics.