The only addition to the combat I would like to see is the possibility of direct control on characters, especially priests and mages. Kind of makes sense that you could tell your prophet what to do
As it is, as soon as your spellcasters revert to AI control you get something of a mixed bag. Sometimes they'll cast some useful spells, other times you'll end up with a level 10 mage, full fatigue and plenty of gems wasting his time casting some low level missile spell or similar ad naseum, or casting various shield spells despite the fact that they are nowhere near the fight.
It might just be me though
If not direct control, I'd like to see some kind of targetting for scripted spells. It would be nice to tell your mage to target the big beasties with the uber damage spell, rather than going for the nearest militia.