If that's what we can rationally say leads to the best metagame, then I'd say yes.
Here's an example of why legalizing walkoff stages could be bad: If we legalize all the stages with walkoffs (or all the stages that are gimmicky, but not broken otherwise, which includes Mario Bros), and it causes a slew of people to quit the game because they don't enjoy it anymore, and we don't have a stream of new people entering the community (because there's not really a community of people who are holding out on playing competitively because Mario Bros isn't legal lol), then the metagame is probably worse off for having those stages legal, regardless of if there's other reasoning behind it.
Now that is a slippery slope to an extent, but do you really think that we'd have more people happy than not with the legalization of Mario Bros?
It's kind of like in the US, ****in' incest is illegal, for no real reason. However if we suddenly legalized incest, the amount of problems we'd gain from religious people causing as much (or more due to the combined nature of it) havoc as they have with the legalization of abortion, in contrast to the small amount of gain due to the very small amount of people who are in love with their brother, it wouldn't be worth it to society to do that. What we would do instead is work on the little things, change the overall mindset, so that something like the legalization of incest could be more well recieved.
This can be applied to a lot of things, such as legalizing, say, pot in ****ing Texas or something. The mindset in Texas (well this one I'm slightly unsure of, as I don't know how well received pot is in Texas lol. But if it couldn't get legalized in California, which is significantly more liberal than Texas, I'd assume that it wouldn't be good lol) would cause that to create significantly more harm than the good we'd gain. Instead we would work on changing the mindsets in places surrounding Texas, working on desensitizing our selves to pot, and attempting to legalize it (as an issue like this is bound to eventually end up with pot being legal in California), eventually it'll spread to Texas, and we'll get the right outcome without the huge backlash, and further stigma.
Or for a more smash related example, it'd be like suddenly turning on all items again if we found our 2003 principles to be incorrect. Or like going for the grab release to spike in tournament matches EVERY time when you never get it. In an ideal world you'd always get it, but in the real world, the issues that arise from trying it would hold you back as a player.
Now I'm not especially sure about the pot example, that one was a random one that came to mind, it's more to get the concept across. The incest one is meant to be the more legitimate example.
There's no reason to suddenly switch to a completely (and probably overly) idealistic view when it wouldn't even cause the best results.