Well there is no way to get 3 shun goku satsu's with 50% health damage in a single round then.
I never knew it was ever invulnerable. Whenever i played any Alpha or Capcom vs. game, i'd get hit out of it all the time. I pretty much had to stun first or punish a wiffed special move in order to hit someone with it. Hell, i even had Zangief final atomic bust me out of it once.
Boss Akuma in ST was invincible during the entire animation. In Alpha, when Akuma became playable it was toned down so Akuma could be hit out of it. But, IIRC correctly, Akuma didn't get the command move until Alpha 2. The initial start up frames to the Raging Demon made Akuma invincible (and it was unblockable), further its faster in the Alpha series than it is in SF4. But the turnaround in SF4 is that it has longer range (and more hits, though still the same damage).
I wouldn't worry about Akuma being too powerful like early Alpha days. He still takes extra damage, and he lost a lot of versatility in supers. His one new tool is the double roundhouse kicks.
As far as the roster is concerned. SF3 was/is ferociously unpopular with the audience that many SF fans grew up with. 90% of the cast was thrown out and a lot of players who had favorites didn't find one to like in SF3. When Alpha 2 and 3 bring new characters on top of the old cast, and were cast aside for SF3, there was a lot to dislike about the roster and the way Capcom handled SF3. Chun-Li even didn't return until the third iteration. Players who stuck with the series, chose someone familiar, Ryu, Ken or Akuma. The huge rise in the Shoto/Ansetsukan players came from SF3.
Much of SF3's popularity now, was something that came about years after it was released. Most praise it for its competitive gameplay systems. But by that point, arcades were dead and SF had lost a great deal of popularity. While its Vs. series kept the Capcom's arcade scene afloat, few deny that SF3 ended up alienating its fanbase that probably would never return. No one denies that SF3 is a well-made game, and that its character roster is has a few good gems. For what it's worth, SF3 is a good game. But the popularity of the SF did dwindle and doujin fighters (of which GG is likened to) picked up the slack.
SF4 is a return to form, really. Bringing back the classic World Warriors, adding new characters and introducing one of the most famous 'dead' characters into SF4 is pretty huge. The gameplay mirrors classic Street Fighter - less emphasis on combos et al - as well introducing new mechanics (and some old stuff) with the attempt to re-kindle the franchise after a near 10 year hiatus. It won't revive the arcade scene in the US, but if it can bring back old fans and introduce new ones into the mix, all the better. It's really hard to argue against the old cast, given how memorable they were. Adding some of the popular (to some degree) Alpha cast members is a nice plus.
In my opinion, it would've been nice if they brought back Karin, Guy, Adon, and Birdie from Alpha. Or at least have Thunder Hawk and Dee Jay return. Even without them, SF4 looks and plays pretty well. The new characters, Crimson Viper, Abel and others are pretty impressive on their own.
Interestingly, I hear the reason why Dee Jay and Hawk don't return is because Ono didn't like them. Never know though, they could be hidden characters.
