That's very relative. In some sense this theme can be applied to every film that I've seen.
That's fair comment in as much as dramatic conflict forms the basis of movie storylines, and difficult choices would create such a conflict. I agree there is an element of the theme of choice in other movies, and in the other X-movies too, though i don't think 'choice' was the main theme of X1 and X2. It could also be argued that X3's main theme was 'power corrupts' as there was a lot of misuse of power in the movie - by Worthington Snr, the president (weaponising the cure), Xavier's mental blocks, Jean Grey, Magneto's terrorism...
The cure itself represents that dilemma of choice - should we be what we are, or if the chance comes to be like everyone else, would we take it? If you were born with fur or a set of antennae or a third eye in the middle of your forehead or a tail or no legs, would you want to take an option that would allow you to fit in - as Beast says, the desire for a cure depends on the exact nature of one's mutation.
The idea of choice is extended into the rest of the movie - Xavier ‘I had a terrible choice and i chose the lesser of two evils’; Storm to Logan: ‘She’s made her choice, it’s time you made yours’, Rogue chooses the cure, Beast chooses to leave the government to be ‘where I’m needed most’ after the president chooses to weaponise the cure... etc etc...
Oh really. So you didn't see the themes of evolution in X1 and X2 that are made obvious from Xavier's intro speeches. I guess you also failed to
notice the theme of the destruction that racial prejudice can cause in the first two films. You also, missed the themes of making choices for good and
evil in both movies. Finally, you missed the themes of using faith or hate to survive(Nightcrawler's scene with Storm in the X2). There are plenty of
themes in the first two X-Men movies and anyone who can't see these themes must be dense.
I regard evolution is a theme of the X-Men as a whole and all three movies; it’s not particular to the first two movies though it is prominent in the
voiceovers. Evolution is also part of Jean Grey’s story in X3 (Magneto says to her in the camp that they thought she represented the next stage in
evolution). Prejudice and good/evil are themes that extend to all three X-movies too. Faith is particular to X2 but hardly a theme of the entire movie, more a sub-theme that gives character to Nightcrawler and some characterisation to Storm.
On the whole, I suppose the theme of X1 is alienation caused by difference and persecution of people for that difference - Wolverine, Rogue, the X-Men themselves, seem like outcasts and people either in hiding or on the run. The theme of X2 seems more like the idea of having to stand together to beat a common threat.
I can also, think of one theme in X3 that is sympathetic to the gay movement and then criticizes it through the obvious message of assimilation. It's no wonder that so many gay writers were ticked off with this movie.
Well, you can blame Joss Whedon for his Cure storyline which was the basis for the movie story. And it is controversial. In real life, there is great controversy over the absurd claims/attempts of curing homosexuality, and controversy over cochlear implants which can cure deafness - the deaf community is divided and many are offended by the notion that their deafness is seen as a disease, despite the fact that it is caused by a medical/physiological 'malfunction' of the ear.
Gay people shouldn't be ticked off with the movie for taking this already-established comicbook storyline. They should have been siding with either Storm or Magneto!