The issue I have with it is that it dramatically changed the way some characters play. It might not look that way on the surface, but some of the mechanical changes to the game turn it into something that isn't ST. Take a look at Honda, for example. He went from being this character who had to take advantage of the opponents poor timing in order to do massive damage with ochio setups. In HDR, zoning meant nothing to him because he could LP headbutt through everything. Ochio was easy to throw out, and the push back from the command throw makes it almost impossible to come out of the corner with the right setup.
This fundamentally changed the way several characters had to fight him. It was such a radical difference that Honda flew up the tier list, because he suddenly had a way to deal with Sagat and Ryu. Other characters got some similar changes, while some just got nerfs for no reason. It's the balance, not the graphics I cared about.
Edit: Also, the core ST version of the game is based on the Dreamcast version of Super Street Fighter II: X for Matching Service. Not a bad version to base the game on, but it didn't give us access to the DIP settings that would make this as close to 100% accurate as it could have been. I also think they screwed with a few of the Old characters. O.Hawk doesn't feel right.