I think the responses thus far have done a decent job of summing it up. It depends on how you play.
I used to (USED TO) play CvS2 competitively on a weekly basis, in both small tourneys and large. After RCing became the most abused glitch in my memory of tournament play, I lost interest. Not because I can't do it, I can, but because it hurt the game dramatically. Sure, I can choose to play an N-Groove BSC team just to win like most other people, but then the game loses something...fun factor. Not to mention how naturally broken some of the characters in the game are w/o RCing. If there are too many glitches/bugs/poorly programmed characters/damage ratios, sure, it can hurt the game. CvS2 is far from "unplayable", in fact it is one of the most enjoyable fighters to play in casual, but at a higher level I can't stand it.
I guess the juxtapostion described in just that one game answers the question for me overall. It just depends on how you are playing and who you are playing with.
My friends and I play SamSho III all the time. It's broke as fuck damage wise and with things like Amakusa's cDx4 "combo", but it's still fun because it is at an admittedly low level of play. Were SSIII to make a comeback and be the next game at Evo or something, I don't think I would throw my hat in the ring, but since that's not the case it's a blast to play.
No fighting game has ever been unplayable to me personally if it is fun. Even broke-ass Heidern in KOF '01 couldn't ruin a solid game from a funfactor standpoint.
Shit, I could go on and on since I'm rambling in circles anyways...
SFIII: TS has karas, but it's still a near perfect game. Garou has Kevin Rian, but it's almost perfection as well.
Just depends on circumstances I suppose
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