I'm might be with Hippieslayer on this one. Nothing personal here, but infzy's philosophy is against a ruleset at all, since the game already have rules. The best smash player is the one who win a (lot of) tournament with 4man FFA, items and all stages, like sakurai want us to play the game (well, maybe not anymore, because of For Glory i think). I'm maybe borderline and ironical on this one, but the game is competively suposed to be played on FD stages, according to the devs. For Glory IS the initial design of competitive smash !
The chess metaphore made me laugh a little, because if you want smash to be the same, better go back to "no item, fox only, final destination" since it's like chess, no hasards, one stage and one (set of) character. My guess is that smash rely on matchups, on different stages, to be competitive, or at least not boring :D.
Back to the subject, I might be a scrub on this one, but i would prefer a game where read, and/or outsmarting your opponent is the core of the game, instead of fighting the stage better than your opponent. Again, fighting the stage is not a well chosen word, as it might mean litteraly fighting the stage (Willy's Castle, Gaur's Plain, ...) or learning stage specific things (like how much time before transition/transformation/hasards ?).
I sure think that everthings not ban worthy shouldn't, but let's take a example : What if nobody want to play on a specific legal stage ? Should it still be in, although nobody giving a damn about it ?
It may just be my opinion, but a stage should be legal because players can use it, not because it's not annoying enough.
On a final note, more stage indeed means the game becoming more complicated (it's pretty obvious), but this isn't the goal of people defending stage diversity. As explained before, the game needs number of stages, and since sakurai pleased us for once with plenty of legal material stages, i would be silly to not taking them into account,. Certain stage require some tests on tounaments (with a S) before allowing/banning them.