Well, firstly, the first ban side argument is a scrub argument. Neither are viable criteria for banning. ACTUAL criteria for banning are:
1) The game ceases to be competitive (basically, the game devolves down to one, possibly random, thing).
2) The game ceases to have variety (Akuma).
3) The game ceases to function (any glitch which makes the game not work at all).
Now, obviously 1 is false - the game is still competitive, and metaknight vs metaknight matches are still real matches, as are most matches with metaknight.
3 is also false - while the infinite dimensional cape glitch CAN render MK invulnerable forever, it is banned. It is arguable that certain things MK is capable of can cause similar issues (planking), MK is not the only character who can do it, just the best at it. Reality is that planking is broken because of the invisibility mechanics of the ledges, and its not a MK specific issue. We had to ban a number of stages due to circle camping, and indeed, if we were to go by the "makes stuff be banned" argument, the #1 offender would not be MK, but rather DeDeDe, who requires us to, by himself, ban every stage with walk-off edges. This is, incidentally, part of the reason that MK is so strong - we banned a lot of stages to deal with DeDeDe which are MK's worst. It doesn't help that the netural stagelist is a bad one - several stages which should be in the neutral stagelist aren't due to scrubby dislike of them.
2 is the real argument, then - overcentralization. And if we look at this argument, it is weak.
22% is a lot, but the idea that it is compared to "36 characters" is just plain wrong. Some characters are multi-characters (shiek/zelda and samus/zss) and some are borderline (Pokemon Trainer). However, the real issue is that all 36 characters will NEVER be viable. At least two of them - Ganondorf and Link - have such crippling weaknesses as to render them virtually unplayable. DK is not mainable because of King DeDeDe, and it is arguable that Bowser is not mainable as well for the same reason, but both are playable in tournaments under the right conditions. So really, you're looking at 32 characters who are really mainable. And it is arguable that the number of unplayable characters is more like 4 or 6.
Beyond that, however, there will always be a best character, and some characters will always be overrepresented relative to others. If you were to ban MK, Snake would make up at least 17% of the metagame, which is not all that much less than 22%. Obviously DeDeDe is far lower, but the same argument could be applied against snake as metaknight - so clearly, just making up 22% is not enough. Moreover, in other games (SSBM, for example), some characters have historically and do make up a huge percentage of the metagame, particularly Fox, Falco, Shiek, and Marth, and at various times have been quite dominant.
Is Metaknight the best character in the game by a significant margin? Sure. But that's not really important. There will ALWAYS be a best character, and oftentimes it will be by an appreciable margin. Ban MK, and Snake will be best. The difference between DeDeDe and the next character is much smaller than the difference between Snake and DeDeDe, and indeed the difference between MK and Snake is smaller than the difference between Snake and DeDeDe. MK is not unbeatably better.
Metaknight does not have perfect recovery. He has extremely good recovery, the best in the game, but there are ways of disrupting it. He can be edgeguarded, but not in the same way as everyone else. There are ways of hitting him out of every single move he has, including the tornado.
As for the argument that MK has no counterpicks, it is arguable that he does indeed have some, such as Diddy, and really, if MK really WAS so good, we'd expect a much higher level of dominance than we see. Not every top calibur player does play MK, which is precisely what they should be doing if he truly is the best. This means that, in some way, they don't think he's a better choice than whatever they are playing, for whatever reason. This does not necessarily mean that he is not the best character in the game, but rather that they feel that he is not the best choice for them to play.
The community favoring the ban is irrelevant, as much of the community is made up of scrubs. Tons of CounterStrike servers ban the AWP, but that doesn't mean it SHOULD be banned - it means a lot of people suck at counterstrike and/or blame their problems on something other than their own lack of skill. Scrubs are scrubs, and tournaments are for competitive play, not for scrubby play.
As for the MK specific rules, the ONLY MK specific rule is the IDC glitch. But it isn't the only character-specific rule. For example, stages with permanent walk-off edges are banned due to DeDeDe (which, incidentally, gives MK a further advantage, because the stages on which his recovery and edgegame are worse are mostly banned), the "kill at 300%" rule exists due to just a small number of things (DeDeDe, ICs), and stalling and planking are not unique to MK - a number of characters can stall or plank, and indeed, we had to ban all of the stages on which "circle camping" is possible for exactly this reason.
Ease of use is, obviously, a meaningless piece of data, and is scrub talk anyway - it doesn't matter how easy something is it use, what matters is how effectively you can use it. CGing with DeDeDe is incredibly easy; does that mean we should ban DeDeDe? No.
I'm not sure why this conversation is even being had. I know the community is incredibly scrubby; EVERYONE knows this except the scrubs in it.