If I may chime in as
someone who stopped playing this game altogether (not because of MK) even though I still liked it when I stopped playing and quit for personal reasons and won't be coming back regardless (basically I'm trying to make it clear how much it doesn't matter to me whether he's banned or not). Recently I've even entered a few random tourneys I happened to be at (because they were also SF/MvC events) just to pick MK and press the B button a lot and see what happens.
First of all, I love playing top tier characters (despite playing Ness for so long in this game); in Melee I played Falco, Jiggs, Sheik, and Falcon, in Brawl I played Dedede, Falco, Snake, Pika, and MK (and Ness but let's forget about that)... in MvC3 Zero, Dante, Sentinel, Wesker, Doom, Phoenix, Dormammu, Akuma, in SF4 Akuma, in SSF4 Chun and Dhalsim, in AE Fei Long, in BBCS2 Makoto, in (... you get the idea).
MK stands out even amongst all of them though because there is literally no reason to not play him. He wins every matchup (by a pretty huge margin for the vast majority of them). If I play Fei in AE I still have to worry about running into Guile or Vega, Zero in MvC3 still has to worry about Trish and Magneto, Falco in Melee has to worry about Sheik and Marth...all of these things could make me second-guess my character choice, and the little mindgames begin before we've even left the character select screen. In Brawl just pick MK...the only character you have to worry about them picking is MK, and even if they do you've already selected the best counter to him.
The issue of characters who are marginalized by MK isn't very important, but it is still an issue. There are really good and fun characters in this game (ROB, Sonic, TL, Peach, probably more) who could all be viable if not for one character (who is again: the only character anyone has any reason to pick if they are trying to win).
The majority vote does matter, especially when it comes from respected TO's, and even more-so when it coincides with the feelings of the community. First of all the TO's are easily the most important people in the community. No TO's: No tournaments. When you have that kind of majority voting for something, it should be pretty clear that following through with it will end up bringing out more attendance than doing nothing (even if it takes some time). More attendance = more money for the people winning and more importantly it's more likely to lead to a longer-lasting game. The real kicker too is that most of the really good MK's should be able to adapt to this quite easily. They are already for the most part the best players and have the most experience (getting farther in a tournament gets you more experience against better players, and the MK's tend to get farther (there are obvious exceptions to this rule, I hope I don't need to point them out)) and it's really not hard at all to pick up a new character in this game.
I think the biggest benefit you're going to see though is counterpick diversity. Not just characters or stages...with MK it's just MK counterpicks everyone on every stage, so have a pocket MK. Without MK you're going to see more varied counterpick duos who are now actually safe to go to their best stages like Brinstar or RC without the threat of MK. Off the top of my head I think these duos are going to be really strong:
Dedede + Marth/Lucario
Snake + Diddy
Falco/Lucario + Olimar
Wario + IC's
Diddy + ROB (Honestly ROB dominates most of the mid-low tier cast almost as hard as MK dominates ROB, and Diddy has some weird matchups against some of those characters)
Basically, expect to see more creative duos and not just Main + pocket MK (which is really Secondary/bait + MK main).
