Hear me out - Action Mode is sick. It's a very immersive experience, with a lot going for it. However, it is fundamentally flawed in several areas, many of which are crucial to the MMO experience.
Number one: Action Mode
does not allow interacting with your UI screens via mouseover. As it is right now, it completely hijacks the mouse pointer to turn the character's camera, disallowing its' use for interacting with Inventory screens or skill trees. They
do have the feature implemented with the Main Menu UI screen, meaning the functionality is there, it's just not been coded for other UI windows. Let me open my Inventory with I, eat some meat with my mouse pointer while I'm walking and close the inventory without
pressing Z to go out of action mode, pressing I to open Inventory, then after I'm done, pressing Z again to return back to Action Mode. It's honestly aggravating after the N-th time, and something that would go a long way towards streamlining the UI.
Also, please add a keybind to temporarily free my mouse pointer. I'd like to view tooltips without exiting Action Mode sometimes, thank you

Number two: self-targeting in Action Mode is difficult. You have to aim in a direction completely devoid of friendly players and/or enemies in order for your target to clear and the spell to proc on you. The arc of aim is also broad, probably to help with target acquisition, but in a target-rich environment, it's a nightmare to clear out your target so that you can safely self-heal. One possible solution is to add a keybind like MMB to self-target, pressing which immediately targets yourself until pressed again, in which case it returns to normal targeting.
If any of you have something to add, feel free to post in the comments!