Street Fighter, when compared to other series (like KOF, GG), has a lot less moves. I mean, Ryu has Hadoken, Dragon Punch and Hurricane kick. His super moves are variants of those. And that's it. Other games would have pages and pages of special moves, different stances and various chains started off with a special move. That isn't Street Fighter's style. Some people would call that 'purity'.

Those of us who grew up playing Street Fighter 2 in the arcades or on our consoles got used to that style and love it. Those who got into Street Fighter after playing other games (like Mortal Kombat) may be frustrated with its 'limited' move set, and thus write it off as 'suck'. That's a little closed-minded, but it's understandable.
This is something Capcom needs to take note of if they aren't already, and make a decision on whether they'll stick to their style, or try something a little new and different to accomodate the way the genre has moved. I'd like to see the game's system updated, but even if it remains similar to how it was before I'd still play it.

As for online play, Street Fighter II is released on Xbox Live Arcade next month. Hopefully they've worked out the kinks and the online play is good. DOA4 on the 360 runs beautifully, even the lag is handled very well. No reason Capcom can't do the same thing for a decade-old 2D game.