Okay... the obvious question is why you took the effort of moving every single skill off hotbar 1 just to replace it with mounts when there are static all-job hotbars which are designed for the job. After all, by default all of your skills are placed on hotbar 1 as you level up so at some point you made the conscious effort to replace them, as opposed to simply having a dedicated hotbar.

For me, I use the higher tier hotbars for stuff like that so this change is a serious benefit rather than a detriment. Having to click to use cannons, for example, in Stone Vigil was a pain in the backside. Now it's so much easier and faster to use skills.

Honestly, this impacts so little it makes me curious why it bothers you so much. Not like you can use 90% of any of those things whilst using a mount or a cannon anyway, and the few you CAN use aren't terribly important. I suppose it wouldn't hurt to make it optional, but it's really very minor.