In my full writeup of the movie, I mention a lot of stuff that recalled BtVS/Angel for me, but I was also thinking, "What am I watching, Serenity [the movie]? Sweeping scope, philosophical quandries, big battles, and killing off characters like whoa."
The deaths and depowerings of assorted characters didn't have real resonance in X3, though.
I will grant that the blase killings off earlier in the film made me wonder if Bobby was gonna die in his battle with Pyro (though I should have known better since he's a Good Guy), but mostly we just killed off large swaths of cannon fodder. All the major character deaths occurred early on in the film (except for Phoenix), and only Xavier got any real mourning time.