Mass Effect 2, a game that's made a few ripples for massively streamlining the entire RPG experience. Superfluous elements like inventory management and sprawling urban areas are excised in favor of a clean yet satisfying sequence of events. On paper it almost sounds as if the game has been gutted, but in play it feels just as full as the last course.
On the flipside, Warhammer Online's streamlining of processes has more than a few people up in arms at the perceived depletion of the game's most interesting content. While we're all familiar (or hopefully familiar) with the basic design guideline of KISS, the argument is being made is that Warhammer Online is simplifying to the point where the fun parts of the game are obliterated.
Needless to say, there's a happy medium to be found, and we can all think of at least one aspect of a game that received some much-needed simplification. What part of your preferred game could do with a solid sweep to get rid of unnecessary complexity? Similarly, what complicated part of the game should remain like it is rather than be slimmed down?