If you could control your troops directly it would be a fundamentally different kind of game - RTS [Real Time Strategy] rather than TBS [Turn Based Strategy]. I personally enjoy both genres, but they are incredibly distinct. The fun of a RTS (for example, Warcraft III) is to try to micromanage your army to maximum effect, using about 6000 mouse-clicks a minute
On the other hand, the fun of a TBS is scripting a battle by giving orders ahead of time, and then seeing how well your best effort at guessing the opponent's tactics does against his best effort at guessing your's.
The two are mutually exclusive - you can't have the fun of planning how a big battle will go down if you have the fun of micromanaging your army on the spot. And they are both fun.
I would probably enjoy a RTS game which had the same units and abilities as Dominions, but it would be a completely different experience from playing Domionions itself.