What's the point of keeping Rarity as a heroine, then having her breaking apart her friendship with the other four, then have Sunset Shimmer act exactly like Rarity used to act, and then have Rarity be friendly to the other four again?
Wouldn't it be simpler to have Human Rarity as the villain, and then introduce Human Sunset Shimmer as the human equivalent of "Good Rarity"?
I'm free to not like the movie, just as others are free to like it.
Part of being a fan of a franchise is having the right to dislike an installment of said franchise, and having the freedomn and the guts to voice said dislike.
Think of all the Star Wars fans that are pissed off at the Prequel Trilogy, all the Star Trek fans that are pissed off at "Star Trek: into Darkness", or all the Transformers fans that are pissed off at Michael Bay's movies.