Miiverse
I would argue that Miiverse is simply a good choice despite the "con" that it cannot be selected because an opponent is using a 3DS as their controller. The instances of someone actually utilizing a 3DS controller are so rare to the point where this con is negligible and shouldn't be taken so seriously.
Secondly, I do not understand why people wouldn't want it in the first place. While it's still the tri-platform stage archetype, it at least has one major difference in the fact that it has a Smashville-like stage bottom, which I dare say is possibly better than Battlefield since it's not as obstructive (i.e. jank happens a lot less). The other con that it has is also moot since it still has a strategy-changing main platform, as well as the fact we also allow Dreamland in the stage list anyway.
Lylat Cruise
If the point of our stage lists is to remove all instances of randomness in the game, then the community and those who make the rules for the game's competitive scene have completely failed at that task when legalizing Lylat Cruise. Lylat is a stage that I've been observing for a long while, and it is possibly one of the worst legal stages in this game, as well as one of the worst in the series. The main problem of the stage comes in the form of various glitches that most commonly occur on this very map.
These various issues include characters clipping through the stage, getting stuck underneath it, hitboxes clipping through the stage, unintentional stage spikes, etc. These issues simply come out at random and catch players completely off guard, no matter how frequently they occur, even. Due to the amount of random elements that can occur, this stage should have been a prime spot for being banned long ago, regardless of if people really wanted it back.
I simply do not understand the appeal of a stage that can glitch out at any moment and ruin a match.