It’s been a while since I’ve played Mass Effect 2, but I do recall being in the Citadel a grand total of two minutes. All right, that’s a severe understatement (no one is dying on my suicide mission!), but it’s true that it’s not as prominent of a location as in the first Mass Effect. That’s not, however, how it always was.
According to Mac Walters, Mass Effect 3’s lead writer, ME2 was originally going to contain far more Citadel content than it shipped with, and that ME3 is going to bring back at least some portion of those lost quests. They were going to be a “callback to the first Mass Effect.”
Walters also talks about the problems with writing a trilogy based on player autonomy and freedom of choice, such as finishing a story where the previous chapter ends with a suicide mission with the possibility of everyone dying. Head over to OXM to read more.