1. It helps control inappropriate behavior.
When the doors aren’t fully enclosed, the lack of privacy causes the visitors to feel like they need to do their private business quicker, which rates up the traffic.
So if you love privacy and think you’re going to use a public toilet, make sure that it reaches the floor. If you are unsure, then it’s best to leave yourself extra time before you go, and make sure that you take extra care when you use it.