Most newer bathroom designs seem sane to me, since they were designed with ADA compliance in mind. Except for airport bathrooms for some reason, where you have to cram yourself and your luggage into a stall that's the same size as any other stall outside of the airport.
As far as I'm concerned, any public bathroom where the partitions between stalls have any gap at all (especially about 12 inches as they usually are) are not sane. There is no reason for that gap; it's just creepy.
It also lets people check for feet before prying open the door.
It's also for if you have, er, a "wide stance" like former senator Larry Craig.
It also saves 12 inches of material.
They could save lots more material by just not having any partitions at all. Why don't they just do that?
As for checking for feet, airplanes solved that problem decades ago with door latches that indicate "occupied" when they're closed.