[Suicide Junkie]

The same reasoning applies to overcomplicated ground combat.

You've got to limit the scope of scales you're dealing with, and not go overboard.

You could have SE4 style with the focus on grand strategy and the combats automated, and the capturing simple.
Or you could have a game focused on combats where the grand strategy is simple automated territory changes based on who wins each round, and the players run a series of fleet battles against each other with boarding and captures being detailed but automatic.
Or a similar ground combat game where the space battle is automated and you can call on reinforcements if your team is winning in space (at the expense of distracting from the space fight).

Trying to do all three of those games in one would make SE5's turn processing look like a blink of the eye.