above illustration of the Ryu sprite for the upcoming Street Fighter II HD Remix shows, drawing good-looking 2D characters in HD requires a lot more attention to detail than the old standard-resolution sprites.
This problem is not exclusive to Capcom. Castlevania designer Koji Igarishi remarked at GDC on the labor involved in creating high resolution 2D art and SNK President Ben Herman lamented in an IGN interview that bringing the company's fighters to the 360 and PS3 would require artists to "re-draw every single older game."
The extra work leads to extra benefits, though, as the sleek new Ryu above clearly demonstrates. Still, the proof will be seeing these beautiful high-def drawings come to life. All the graphical fidelity in the world doesn't matter if the animation is on par with Star Wars Adventures.