Abilities activating during the enemies' turns would be cool, but we already got something like that in D:OS with attacks of opportunity, ground effects and such, am I wrong?
Apart from that, I think that the turn-based system of the first game was fine as it is, and it was also very well received by fans and casuals (one of the highlight of D:OS), therefore if something is not broken...
I noticed that you mention XCOM quite a lot; personally I don't think Divinity should borrow much from that series, both in turns' organization, timers and dynamic battle cams (nooo!).
