(Keep in mind this will most likely be a TL;DR post)
The OP keeps saying that people quit over certain characters or tiers, but I don’t think that’s true at all. If people were sick of tiers, the 3s scene probably would’ve died around 2005, nobody would still be playing ST, and SF 4 would already be recgonized as the garbage that it is. Here’s why I think a lot of players (not just pros/vets) are no longer playing 3s:
1. It’s an old game.
3s came out back in 1999, exactly 10 years ago. The pros/veterans have been playing it for a long time, and either:
A) They have already reached the top, so they don?t really have anything left to prove or achieve.
B) They have grown up or gotten into a certain point in their lives that doesn’t permit much game time.
C) They are tired of playing an old game (they?ve ?learned everything? already and have no more motivation to play). We now have plenty of games like SF 4, STHD, Blazblue, KoF XII, and other new games that—although not nearly as godly as third strike—are new, quality fighting games that anyone can learn and enjoy.
**2. The FFA 3s scene died quickly. **
I think a lot of people in the U.S. were motivated to play 3s by seeing the strength of the FFA scene between 2004 and early 2008. There were always plenty of tournaments, plenty of entrants, most people played at a pretty high level, it had excellent videos and commentary, and there was even a podcast dedicated to leveling up your game. All of these things displayed how much everyone loved 3s in socal, and it motivated/inspired players to try and get good like the stars of FFA. Even if you didn?t play or care about 3s, the hype and activity of the scene was intriguing and made you at least want to watch the videos, listen to a podcast or attend a ranking battle.
Soon after SBO 2008 last year, SF 4 came out and Denjin Arcade opened. With the opening of Denjin Arcade, all passionate 3s players said ?fuck FFA? (for good reason) and swarmed to the new hot spot of socal. Unfortunately, we lost some important figures in the process: Rockefeller, Pyrolee, Amir, Arlieth, Shadini, and a lot of other really good players/supporters of the scene. A lot of regulars at FFA did not join the transition from FFA to Denjin Arcade, and thus there were a lot less tournaments and a lot less entrants. FFA Ranking Battles were no more; Tom C., Gootecks and Shogo did most of the work for the brackets and videos but each of them were onto bigger and better things. Gootecks changed his 3s podcast to a ?Street Fighter Podcast? (nice way of saying ?Im gonna stop 3s and mostly cover SF 4 now?).
There was little awareness of the first Denjin Arcade Ranking Battle season. There were only a couple videos recorded, they weren?t edited, and there was no commentary (the only one with commentary had extremely terrible audio quality and you couldn?t hear anything). Although the Denjin 3s scene was amazing, from an online perspective it seemed like it was nowhere near the level of hype of FFA back in 2006. At this point, a lot of people in the U.S. saw that the 3s hype was dying, and I think this made many of them lose the motivation to keep playing. They assumed that 3s had already reached its peak, and now it was time to move onto something else.
3. 3s has an extremely high learning curve.
Most likely, the biggest reason why we don?t see very many new players is because of the time and dedication it takes to get good at 3s. Even if you have a general knowledge of Street Fighter, if you put a quarter in a 3s cab at Denjin Arcade on a Friday night (without ever playing 3s before), you?re going to get owned no matter what. It?s not an inviting game because it forces you to lose for a long period of time before you really start leveling up.
With SF 4, pick Sagat, pick Zangief, throw out some fireballs/uppercuts, press 3 punch buttons, try to do that ultra thing, and you already have some wins under your belt. It?s flashy, has nice graphics, and when you win the game makes your scrubby ass look pretty cool. A game like that makes everyone want to play it. But as far as 3s goes, you have to know the game to appreciate the game, and as time goes on (with much less attention on 3s and a lot more on SF 4) it becomes harder and harder to find new players that want to learn and play 3s.