Frankly, I think the problem of knowing "where" is less important than it seems. There are plenty of pieces that demand the player move their hand pretty far without much opportunity to feel for placement. Eric Satie's Gymnopedie No.1 comes to mind. I find that fixed seating tends to make this a non-issue.
Even so, we could add nubs. There isn't a law against it.
> it's a feature not a bug that a b minor feels different in my hand than an a minor
But should it? After all, they are both the same Aeolian mode. They sound the same, excepting only that they are in different keys. Shouldn't they feel that way, too?
> Makes it easier to look over one's shoulder and know exactly what chord they're playing too!
Does it?
It's pretty trivial to tell what chord a guitar player is playing, even if it's a bar. I don't see any reason it would be more difficult with a homogeneous piano/keyboard layout.