I still don't really know why SFxT failed. Watching players like Ryan Hunter play makes me interested in the footsies, although I can't say I like other things about the game. I don't have nearly the amount of understanding that they do though.
SFxT failed for the simple reason that it's made to be the anti-SF4 and to satisfy the SF4 complainers. Which is why they nerfed the throw ranges, nerfed the wakeup game, remove ultras, got rid of FADC uppercuts, got rid of uppercuts through block strings etc. The most ardent SFxT supporters always praise SFxT for how much more fair and forgiving the game is compared to SF4/MvC3 and how you have to work hard for the comebacks unlike those games. Problem is, being fair doesn't necessarily make a game fun. When you get bodied by nonsense like vortexs and frame traps the scrubs complain and moan, but the non-scrubs have the motivation to work hard and learn how to beat them. No one gets that motivation in SFxT, because that game is just too fair. You see Ryan Hunter, JiBbo and co rant about how we are doing it wrong, how we need to _____ for max damage, how we shouldn't waste our meter or our red health...... tell me, does anyone actually give a flying damn about all these?
And the worst part is, the balance changes they have done so far and are thinking of doing are all attempts to satisfy the complainers who themselves have a shallow understanding of how the game can be fixed. That's why they are nerfing tatsus, Rufus dive kicks, Rolento's jabs etc and are making the game even more fair and less fun when they should instead be doing the opposite. Things like the standing jab pressure could have been solved very easily by buffing the throws, something which they shockingly seem to have never considered.