10 bit isn't necessary to take advantage of a wide gamut screen.
Cameras can capture wide gamut and printers (inkjet) can print it, so it makes sense to have a screen that can display it (if you're a photographer printing to an inkjet).
Exactly. A 10 bit display can display more colors no matter what. And of course you only can take advantage of it if you're a photographer, graphic designer or something like this - that's why those screens are there.