You just don't care.

Film "See the problem is that a LOT happens in this film that should have enough of an emotional impact to make you feel like you've been kicked in the gut. Except it doesn't. At all. And that stinks because with the things that happen to characters we know in this film we should leave the movie theater dumbstruck and shaking our heads at the losses." -- ScreenRant puts into words what I somehow couldn't about X-Men 3. I think they were just trying to do the Serenity thing and somehow misunderstood how that was achieved.