why is this forced on us and not an option?

[kyuven]

As part of a quality of life improvement in Patch 2.5 we made it so when interacting with objects that feature actions (such as the cannons found inside Castrum Meridianum) the abilities would automatically appear on your hotbar/cross hotbar, instead of being displayed exclusively on the pet hotbar.

However, as you pointed out, we have confirmed that this change is happening to field mounts as well. We are planning to address this issue and we will update you as soon as we hear more!

From another thread.
They know it's an issue, but since it's QoL more than anything else, expect it to be low on the priority list til the next major release.

this screws me up almost as bad as the pet cross hotbar did which is why I disabled it and have my game set to keyboard/mouse with all 10 hotbars showing and the pet hotbar as well, and he cross hotbar enabled.
yeah I probably would have had a great deal of issued on the PS3 version

Also, 10 hotbars? What are you using 10 hotbars for? I play multiple classes, multiple crafters, multiple gatherers, raid final coil, etc. and I only use 3. the most I've seen is four or five tops, and that's mostly for tanks and people with a ton of raid macros.
Why do you use that many hotbars? And why is your non-combat stuff on the primary hotbar? You do realize you're actually setting yourself up for situations like this precisely because the game focuses on that bar, right?