Well think of it this way, I could consider Town and City's platforms to be hazards. They serve similar functions to Umbra Clock Tower, which is actually banned. Then there's the comparison between Gamer and Arena Ferox, and despite being in different consoles, one is banned and the other isn't, despite the latter providing disruptive obstacles such as walls between characters and caves of life.
Then there's Delfino Plaza, which has a low ceiling and a walk-off, but then you have Prism Tower, which is the same thing, despite being in different consoles, and Prism Tower is legal. The problem is, is that people have double standards within Smash for Wii U and 3DS as a whole, and that needs to stop.
We ban UCT but not Town and City, we ban Gamer but leave Arena Ferox alone, and then we ban Delfino Plaza and let Prism Tower be allowed. There's a huge double standard, and if not that, we have Battlefield, Dreamland and Lylat, three versions of the same stage layout, all legal or CP, but Sakurai forbid that Miiverse is tournament legal or CP.
But then again, who wants to point out the double standards when we can just ban more stages into a too-cramped list?