This comes from the viewpoint of someone who loved the idea of a blended base build (like AOE) and something more realistic - I’m loving the more coordinated attacks of AOE4 and Wall building, but think these would really improve gameplay:
Accuracy (and lack of): Having 30 archers all hit the same man you happened to click on isn’t half as useful as the arrows falling and wounding at random. I also (having lost a load of cavalry to a mangonel while they were chopping up some archers) miss friendly fire from artillery. It’s realistic and makes random shots landing here and there during sieging a little bit more epic. AOE III did this well with cannons at a range (at least when I played it back in 2004)
Attacking squadrons rather than individual units: Having a load of pikes charge for one man rather than meeting a battalion as a line also takes away from the joy of battles I find. Rise and Fall did this well - you built units as individuals but when grouped they engaged other battalions as a cohesive unit. I know ‘it’s a game’ and ‘not TW’ but think it looks better and plays better.