This is why I like the idea of Professor MAR Barker's Perfected Game Rules, which the inestimable Timeshadows posted yesterday:
Prof. Mohammed abd Rahman Barker's Perfected Game Rules:
1) We both roll dice.
2) If you roll high, your view of reality prevails.
3) If I roll high, my view of reality prevails.
4) If we're close, we negotiate.
Of course, these Perfected Game Rules require adherence to my Don't Be A Dickhead philosophy, i.e. it requires that both parties be friendly and reasonable people who have social skills. But I'd like to give them a try some day.
Their chief advantage, apart from the fact that you don't have to arse around with things like game books and stats, is that they add another crucial human element to the game. Negotiation is a huge part of what makes games like Diplomacy so great, and is a cornerstone of human interaction; done correctly it is always mutually satisfying, like most other cornerstones of human interaction. (Especially the one where two people engage in naked bed top wrestling.) The fact that it isn't a major part of a lot of rpgs is a sad consequence of the fact that the hobby seems to attract a proportion of dickheads (because you need robust rules to deal with them), but it doesn't have to be that way.