I already posted here, but I could go on for hours:P
I mentioned time before... this is in relation, basically, to simple believability. I don't want my sense of disbelief broken. The fact that everyone's always in the same place every time I visit somewhere drives me nuts. The game needs some Oblivion-like AI to allow PCs to follow patterns. Work, sleep, eat. That sort of thing.
As far as the affect on the toolset, some basic standards can be built into it to accomodate this. Adjustable through scripts, but basic functions could be standard... set a person's home, hours of operation, work place, etc.. and different conversation trees depending on state.
I.E. I create an NPC, flag a given room as "home", another room as "Work", and draw his path. Totally optional, of course, and an individual module creator could simply skip over this, but it'd be nice to have it in-game. A living, breathing world, so to speak.
Preferably with changing political climates.
Let me take the existing game for example. Say I take entirely too long to get to the top of the tower at Ostigar... the overall storyline doesn't change much. When I do get there, I look down out of the tower on a lost battlefield and Loghaine's forces marching away from the battlefield. We have a slightly altered conversation with Morrigan and Flemeth, and otherwise we move on... but it add's a lot to the dynamics of the game.
As I'm wandering Ferelden looking to bring people in on treaties, I see the encroachment of the Darkspawn on the world map. As I enter areas that the Darkspawn have already reached, they are overrun. We would have to come up with reasons why key areas aren't affected yet, but there's no reason several areas containing just side quests can't exist... or maybe if the elves are overrun before I reach them, I simply cannot complete that part of the quest, leaving me at a disadvantage in the final battle.
I guess I'm asking for a living world, but a living world in which time is a factor. No video game has every really used time much... I guess because if it's done well, and you get too far gone, then it becomes nearly impossible to finish the game, but I do advocate a limit to this... still, a nod toward some sense of urgency would improve things, I think.