Yeah, even in very visually simple games that don't need to worry about visual assets as much and have strict end points, like text adventures and ChoiceScript titles, meaningful choices rapidly leads to exponential addition to the workload. For an MMO... as much as I'd like the ability to have a bit more room in dialogue choices (I haaate having two options that are basically rephrasing the same thing without personality variance, especially when the non-choice isn't part of the joke), it also ends long before choices that would cause actually big changes just because of the workload involved in a game like this. Either you have to collapse stuff, which would piss people off a lot (as we've seen with Mass Effect), or you have to keep adding more and more work to the pile as you move forward.