In AoW 3 you do get double XP for 1-shot abilitie (say, Crossbow), and using touch abilities also gives double action XP.
I don't think, making it "micromanagery" is wrong, because in a system like that used in AoW 3, with unlimited upgrades, but limited amount of XP, XP is just a resource like everything else, and getting the most out of it is essentially not different from picking your settlement place. There is nothing wrong with getting more out of battles when you put more effort into it. It just shouldn't be exploitable, yes, but otherwise, getting more XP out of your battles has something to do with SKILL
The problem is, the moment you realize that XP is in fact A RESOURCE, it has to become part of the game's "difficulty structure" - if you CAN play to maximize the gain of that resource, then playing on higher difficulty means, players have to actually be good at that or don't get very far, and that's where it starts to become a problem, because clearly this is putting a lot of emphasizing on the battle part of the game which is probably unwise if you want to cater to a broader public.