I think most of the calls for tactical come from a desire to have a bit more depth to combat that in GC2 - where you just built as many of the biggest ship you could build/afford and slugged it out.
I'd add the ability to set unit behaviour and to set target priorities. So, if I've got a colony ship, I can tell it to try and escape, rather than fighting it out. Or tell my ships to concentrate on taking out a single ship - like, say a transport.
That could all be done at the start before the combat viewer and would make the battles in the combat viewer much more interesting without actually adding any real amount of tactical control over GC2.
It'd also provide an impetus to have a wider variety of ships, allow for different play and construction styles and generally prevent a drive for the biggest ship with the best guns and mean that engines, sensors, terrain and support modules would play a bigger role and it'd help the AI and player better strategic decisions on how to attack & defend.