Because I don't like the cast, director, campaigning strategy, aesthetic of the stills/trailer, genericism, promotional materials, or maybe disinterest in the subject? I don't have to justify not wanting something to do well( we all do it and it is completely valid.
For example, despite being a huge feminist, I didn't want Suffragette to do well because I'm apathetic towards Mulligan and it looks like this year's Imitation Game.
I also dont want to see Depp in contention this season because I strongly dislike his filmography and think there are much more inspired choices.