Maybe I wasn't clear - I've edited a bit to be a bit more clear, I was specifically on about the smoothness of the mounts. How the mounts feel connected rather than like one moment you're going north and a key press later it's 180 an entire whale on one pivotal point.
Its for the feeling. Also beyond that just to argue against your point, it could do something - there are points of time in the game where you can't fly. But the purpose wasn't to argue for that. In addition unique mount abilities wouldn't become pointless, people use the sneeze on goobbue and that's "pointless" (flavor != pointless) but priority argument wasn't that we need to have a bunch of movement abilities as the priority was on smooth controls (though some flavor movement abilities would be a really nice bonus that I'm not against).
It was like "I really want smooth mount controls" and if you could do these other things that could be fun too (valuable progression depending).
Alternatively think of it this way, the glamour system doesn't really do anything then (under the concept that having an optional mount system doesn't do anything).
So of course it does actually do something as visuals are important. A car that drives a bit closer to a car (like how GW2 mounts control different) would feel /a lot/ better (to me) than a car or whale that 180 swivels on the spot and veers violently when you change direction with a key press (control with camera helps smooth out the ride, a bit). It could do more, like progression similar to how GW2 has but it doesn't have to (as pointed out we have no flying zones, until we unlock them, and some zones are always no fly). Of course being part of progression would take some of the optional concept out of it.. which is both good in that it's a new way for the devs to present their world and bad for those who don't want it. I'd want it but I wasn't initially looking to lock people into a life style choice by asking for smoother controls and more mount flavor lol.