My experiences playing competitive Brawl in the Midwest tell me that, as the stage list shrank, the general support for the game shrank too. There was a lot going on culturally with Brawl, but I have no doubt that banning too many stages really did very significantly harm competitive Brawl far moreso than having too many legal ever could have. It made the game grow stale quickly (there's just less going on when you play on a tiny fraction of the stages), and it super emphasized the strengths of a few of the "best" characters and greatly hastened the metagame contracting around those to the exclusion of otherwise good characters who preferred now banned stages. I mean, no one really wants WarioWare legal; that stage is super random and significantly detracts from the skill test of the game. How about Jungle Japes though? There is literally not a single random element in that stage (Klaptrap is on a timer), and the different layout adds to the diversity of the game by emphasizing diffrent character strengths and weaknesses than Battlefield and Final Destination. I actually like playing on really crazy stages in smash games, but I can accept banning a lot of those and only really get upset over the thing when we start just banning way too much and taking away stages that have nothing of real signficance wrong with them, something I'm quite convinced hurts these games way more than leaving too much legal ever could.
I mean, seriously, there were Brawl tournaments that banned Halberd and Delfino, two super obviously fair stages, and when I main G&W and those are good stages for me while terrible stages for me like Smashville and Final Destination are always legal, it begins to feel unfair. People talk like there's some abusive stuff that's so good on Halberd and Delfino; I just see how Smashville and Final Destination make the most abusive thing in competitive Brawl (Ice Climbers infinites) as easy as possible which is just obviously "worse" than anything on Halberd or Delfino to the point that the Halberd and Delfino bans wherever they exist feel totally arbitrary. I put thousands of hours of work into G&W with the assumption that the rug wouldn't be pulled out from under me and the rules redesigned to be literally the worst possible ruleset for my character; I'm not even bitter over it because Brawl is all in the past, but I don't want something like that to happen to anyone with the new game.
The main thing I want from smash 4 stages isn't to have every stage I could ever want to play legal. I just want to have a real diversity and to keep everything that is reasonably okay. I can accept playing on signfiicantly fewer than 30 stages. I can't accept playing on 5. Everyone can get most of what they want out of stage rules in the new game. Stage liberals like me can have the gameplay diversity (and also not see characters who like dynamic stages just get screwed by the rule changes like in Brawl). The stage conservatives can have their game where we don't have significantly random or disruptive stages. We just have to all accept not getting every last thing we want and instead take that reasonable middle of the road option where all sides get most of what they want (note: this also means no constantly shifting rules where we "compromise" and then later one side takes everything else they wanted). This probably means a number of legal stages somewhere in the low teens all fully legal (that means legal in game one), and I'm quite convinced smash 3ds offers enough quality stages to make that happen even with what little I know now before the US release and would find it surprising if the Wii U version weren't the same way.
Starting off we should play with a very large number of legal stages just to get some real and serious experience about what's going on on all the different stages, we should discuss them all as a community, and we should find that set that is going to result in the greatest outcome for most of us. Jumping the gun on banning stages all over the place is going to make it very hard to discover what stages are actually any good; there seem to me to be around 20ish 3ds stages with some prospects of quality. I really doubt all of those will work out, but I don't think we'll know which of that set work well and which don't if we don't just try them all and hash it out. If we just instantly only play on 5 of them, I guarantee we're leaving a lot of good stuff on the table, and the game is just poorer as a result.