Would you mind elaborating on what makes III so bad though?
Multiple things, but I'll just boil it down to the main issue: The Mechanics.
Almost all of Capcom's fighters (Super Turbo, the Alpha series, Darkstalker/Vampire series, and the vs series) were all about fast-paced action and being on the offensive with attacks instantly coming out the moment you pressed the button, even on some heavy punch/kick buttons. So majority of matches were combo-filled slugfests. III was made by a team that had no experience on making a fighter, and the team that made Super Turbo and the Alpha series were no longer available, which is NEVER a good sign. The inexperience shows though because III dials it WAY the fuck down. Firstly, now every character has additional frames of animation, which on one hand might be visually appealing, but now you have to account for those additional frames when attacking, which halts things a bit and forces you to re-think your strategy unless you're just mashing jab punch/kick all day. Combine that with the general movement of the characters when they walk/jump/croutch, and they just feel sluggish, like all of that extra movement is unecessary (which it is). Just to note, SF4 and SFV are even more slow, and it has nothing to do with 3D since other 3D fighters like DOA and Virtua Fighter have no problem being speedy fighters, and even Fighting EX Layer does a better job at being faster than SF4 and SFV. So for some reason since III, Capcom has been reluctant to increase the speed on their fighters for whatever reason.
But the worst offender is Parry. THIS kills any offensive strategy and chops the legs off of any offensive player because now you essentially have Samurai Showdown minus the weapons in which you're just shuffling back and forth poking each other, only this time it's a game of "who can parry the other person's move first", so it forces you to be defensive and artifically extends the fights for longer than they really should be. The funny thing is when you look at SNK's 3rd strike "Garou Mark Of The Wolves", a game that ALSO has a parry mechanic (Just Defend) the matches that take place in that game are the complete opposite of 3rd strike. No one is afraid to go ham in that game and fuck shit up.
So what you essentially have now is 3rd strike's fighting style anmd the mindset of people that play 3rd strike seep into other fighters that weren't meant to be played like 3rd strike, including older ones like Alpha and Super Turbo. I've had people from 3rd Strike jump into ST and bitch that they can't throw people, or say the game sucks because it's completely broken, but 3rd strike is perfect (which it isn't). Tourneys suffer from this as well. If you compare Japan tourneys to American tourneys it's night and day. Gamespot Versus, a japan tourney held every week, has players there going ham at each other even with supposid "low tier" characters. They are cool guys that get in your face and doesn't afraid of anything. American Tourneys, including FightCade ones, are just matches where two guys are hugging the wall mashing the jab button or projectile spamming each other.