I would suggest playing mario circuit more; the stage isn't random. If you played Mario Kart 8 you might be familiar with it, it's in a "track" format
We also don't ban items due to "luck factor"; if we banned things solely due to luck we'd remove Peach and G&W. The two biggest reasons stages are banned are things called "overcentralization" and "degenerate gameplay" (which is really a specific form of overcentralization...).
Oddities, unique traits, or one-off events typically don't ban a stage. Smashville can kill ness (up+b hits balloon), Duck Hunt can kill zelda if she up+bs in the dog's location while he appears, etc., etc., but they don't mean 'ban this stage' because they haven't shown overcentralization or degenerate gameplay. No one CPs Ness to Smashville so the balloon kills them.
"Gamer" is banned because it centralizes almost solely on the "mom" hazard; after you play on this for a long time, strategies develop that is solely based on the mom hazard and these strategies become less of a "I know the stage and you don't" and more of a "You have to deal with this, forever". It becomes an integral part of smash brothers on that stage.
Spiking someone who fell in the water in Delfino is a stage-related strategy as well, but the game doesn't centralize solely on that strategy. It's a thing that can occur there, but it isn't what the stage
is. Just an extra factor.
"Palutena's Temple" or whatever the 8 player stage is is banned because of "degenerate gameplay". The optimal strategy is to run away and move out the timer. Running away with Fox works as a strategy, but it is THE strategy on a stage like Hyrule Temple in Melee -- degenerate gameplay. Great Cave Offensive is in a similar boat with how you need to kill people with the fire.
Wuhu Island is a stage that I believe is already suffering from degenerate gameplay in its first stages. The majority of the transformations encourage stalemates and the size of the stage makes a timeout a near-optimal strategy. I could be wrong on this.
If we played Circuit more, got more familiar with the stage, and then all out matches became determined solely by stage factors outside of our control? Sure, it'd go in the ban pile. But so far all I've seen is a normal moving stage with a car hazard that moves in. By all means though, on the 27th you should come up and play some matches against me there and show me the negatives you see in person.