Brandon Sheffield has a great interview up on Gamasutra with Yoshi Ono, producer of Street Fighter IV (among other things), on the franchise, the new game in particular, and on the genre as a whole. There's plenty of technical stuff dealing with transitioning 2D games into 3D, but also discussion on why it's a pretty lonely proposition to make fighting games these days and on making fighting games more accessible and less off-putting to a wide audience:
What we've done this time is that we kind of hit the rewind button and went back to Street Fighter II, because I think we're used to that. That lowers the hurdle for people who are familiar with Street Fighter II, but it doesn't necessarily bring new people.
We haven't done anything terribly special. What we really need to do if we want brand new people playing fighting games, is we need to simplify things to the point where they no longer have to rely on looking at the manual.
Perhaps less buttons is the key, or perhaps less special moves is the key.
Really, we just need to focus on the idea of reading your opponents' moves. People would understand the fun of that, and it doesn't require a lot of special moves. It needs some kind of general simplification to get more people into it at this point.
It's a nice, chatty interview — a breezy read with plenty of substance. Certainly worth a read whether you're a fan of the series — or the genre — or not.