I can understand being disappointed that the story is diverging from the comic, but to me - a non-comic reading fan of the movies - Kitty had no bigger a cut in her importance than any other character that wasn't one of the 4 focus characters. I've only ever watched the movies (and the 90's cartoon), so Kitty Pryde is a minor character in the continuity I know. She was certainly important in the original comic, but she's never been a main protagonist in the movie continuity, so this didn't seem all that bad to me.

imitarate commented on this that, with comics, you've got years to build up everyone to some extent, with the ability to make them all the central character of their own arcs. With movies, you've got 2 hours every couple of years (if you're lucky) and if you branch out too much, or too quickly, you lose people. It's just not possible to do the same justice to all the characters in a movie as it is in the comics. The movies are appealing to comics fans, but also to people who have never read a comic book (like me). I don't have the background to understand how/why most of the characters do whatever it is that they do - I had to have Imit explain what Bishop was doing in DoFP, and what exactly Warpath's deal was - so switching to someone else as a central protagonist would be jarring, at best for me. Since I don't know them, having Mutant 563 be the one I'm supposed to care about and empathize with is a harder leap if I'm used to the Professor and Wolverine, and I don't see Mutant 563 in some sort of context with them, first. Introduce me, then send the story off in the wake of Mutant 563, and we're good. :)