Some people just didn't like the way she looks with a pair of oversized wing, the crappy rationale for the change, the unpleasant implications or the further cheapening of the alicorn myth.

And yes, I am fearful for the potential ending of the series, since many stories I liked ended on a shitty note. I know that many folks may want something like this, but one of my biggest fears is that the show will end with a massive time-skip epilogue to the future, where Twilight is all tall and sparkly like Celestia, picking a new character to be her student, since it would confirm all the problems I had with Twilicorn in the first place.