Don't care. Obviously SMB 2's levels are different but they still accommodate all four characters just fine in different ways, they could figure out a way to do it with a mainline Mario game but they won't. I don't care if the current traditional Mario level set needs a slight shake up in order to make it happen or if they would be better off just putting her in with the same abilities and keeping the standard level designs, either way it's lazy that she's not in the game. End of story.
More willful ignorance. Shoehorning different types of characters into the game is not the way they wanted to do it, and it's not a lesser game for not being playable with tons of different types of characters that can float or double jump or teleport or whatever. Sticking Peach in there would make it a worse game for Mario, because it would no longer be able to be designed entirely around him. And now you want her in there as basically a skin, so I'm going to take your moving of the goalposts to mean that you really do understand what I and others are saying but you don't want to admit to being wrong.