Well how long has it been? Three years since brawl's release? Granted MK is still the best character by a relative margin, everyone has 'strategies' to overcome that character, yet the argument of him being banned or the game being unplayable and boring overall seems to be a constant factor in discussion.
I guess the question would be is the game [Brawl] competitive; I certainly think so, however many people (granted, a large deal of them being melee players who only played brawl during the first month or two) think otherwise
People weren't initially crying "OP" because of his tilts, N-Air, perfect planking, or complete dominance on counterpick stages. They got around Tornado, Shuttle Loop, and edgeguarding potential, and then other things were found and not taken as seriously for some reason, even though they affect the game much more and cause the other things to be significantly better than they were on their own.
I still think he should be banned, but only because more things have come to light. Meta Knight's F-Tilt shenanigans really make everything else exponentially better. Everyone continues to say, "The metagame has settled--You'll be okay," when the game would be much healthier and much more exciting (IMO for the latter, but, come ooooon) without him. M2K placed outside of top 8 at Pound 5, probably because other excellent players have decided to pick up the god character. Ally regularly beats M2K now that he's switched, for instance. M2K practices probability, and sticks to what's guaranteed; if faced with something new, he panics and does not adapt.
I think people have just become desensitized to it, suggesting, "If he hasn't been banned yet, it'll never happen," and so the argument is just swept under the rug now because of it.