There's a very thought provoking post over on the Terra Nova Blog by Timothy Burke which looks at the pros and cons of complexity in MMOs. Mr. Burke begins by saying that part of what makes MMOs arguably more entertaining than single player games is the inherent complexity that comes with the genre. That complexity is a draw, and it's a good thing - up until a point. When a game becomes so complex that not even the developers can see the whole picture, then you have a problem.
Ive found that virtual worlds, massively-multiplayer online games (MMOGs) have provided some great examples of this kind of Rube-Goldberg complexity-by-design, and have also demonstrated why this phenomenon can be a source of so much trouble, that you can end up with systems which are painfully indispensible and permanently dysfunctional, beyond the ability of any agent or interest to repair.
Mr. Burke uses Star Wars Galaxies and Warhammer Online as examples in his thoughts. All developers would do well to listen to what he's saying here, if they aren't already aware of the problem.
For the full blog post, please visit the Terra Nova Blog.