Which characters can actually use walk offs for kills as such? I know that King Dedede and Yoshi can against select characters, and Falco can at the right percentages if he starts close enough to the edge (Falco also can if they really screw up and get laser locked). I have heard some reports of Fox being able to do so with jump canceled shines, but I've only seen a video of it happening on an extreme slope. Note that no one I listed is among the best characters in the game (though several are good); in melee, the single best character in the game was the one who got better this way. I think that makes a big difference. For instance, on Bridge of Eldin, would you honestly say that King Dedede is an overall better character than Snake or Mr. Game & Watch? If he's not, then the tactic isn't the most overpowering thing on that level. Why ban something that's only of secondary worth? I'm not saying that if it was the best it would deserve banning, but if it's not the best, a ban becomes really unpalatable.
Also, consider accessibility. On Distant Planet, there's one walk off that is interrupted by rain with a slope that messes up several of the chains that lead off the stage (I am pretty sure King Dedede can't chainthrow Marth there though he still gets Donkey Kong; I alone can't really test this in more depth; it also probably messes up Yoshi's release grab on characters like Meta Knight - Falco's laser lock obviously doesn't do anything there either). On Onett, you never have to approach a walk off thanks to the cars, and the walk offs are conveniently out of the way anyway. Even if walk offs are concluded to be broken, I really don't think these two levels should be banned without far more careful review. Of course, even a level like Bridge of Eldin or Mario Circuit can use hazards to screw things up. Did you know that a King Dedede chainthrowing in the bottom area gets interrupted by cars on the upper segment of track when he's near the edges? Further, consider temporary walk offs as on Delfino Plaza and Castle Siege. It's completely plausible to simply avoid danger until these pass; they really shouldn't be lumped in with anything either.
In any case, I think they need more time to prove themselves broken. Banning stages because of hypothetical problems is a fine way to assure that the stages are never fully understood; it's better to let time to shed some light on the real potential of a stage before it is given anything but the most generous benefit of the doubt.
