Players like to be presented with meaningful choices, make decisions, and SEE the effects of those choices.
For example, I never bother to add extras to GCII ship hulls (other than to add needed hardpoints) because those choices have no meaning, no significance.
In a first person shooter, choices of which weapon, which path, etc. all provide significant feedback. If one chooses the uber shotgun for close combat only to face an enemy in a long hall, ....
GCII, with for example its good-neutral-evil choices, contains some very nice and novel elements of the above sort.
Other standard choices include limited resources, limited planet space, trade-offs in economy models, research decisions, etc. The inclusion of worlds not immediately able to be colonized is good, but it might have been better if some races were native to non-O2 environments. as it could add more depth to some alliance situations, etc.
Some players like to make lots and lots of decisions. A game in which one has constant external decisions like the good-evil-neutral ones in GCII can immerse or annoy. Which mayor should I back for this town or that, or which petitioners should I grant an audience, etc. can be worked into aspects of the game, sort of like how in GCII the leaning towards evil or whatever can, or breaking a treaty.
Other players want to make fewer but more meaningful decisions, and then enjoy the implementation. Which weapons trees and hulls, then go out and try to kick butt.
Being able to "turn off" events or throttle them, and make similar choices in the set up at game start is probably a must to get a wide enough player base to be viable, but the game has to be deep enough to enjoy in all the possible modes.