Originally Posted by psylockolussus
Well all of them were introduced before in the movies and none of them died in X3. I don't think it has something to do with staying true to the line-up of the comic version.
They could have used the fan favourite Nightcrawler who almost everyone has been asking, same as Kelsey's Beast, or even Gambit.
Since the movie is set many years after X3, they wouldnt need to explain why some characters are there and why others arent.
But they have confirmed curiously 5 of the characters from the comics. It isnt just a coincidence.
Matthew, Singer and Kimberg could have left Kitty out, since Ellen only appear on one movie, as some fans said many times these past months, but they decided to included her. It should be for a reason, the biggest one because she is a pivotal role on the storyarc, and many fans would have been pissed if she was out of this big sequel.
We could say the same as Colossus, since he was just a large cameo on the trilogy.
We know Fox has made many wrong decisions during the decade, but some other decisions have been intentional, specially from Bryan, like using Havok, Beast and Banshee, even if some fans try hard to say otherwise.
And if Boo ends playing Thunderbird, that would be another example.
Only time will tell, once Singer starts doing interviews and on the DVD, talking about the characters they choosed.