Great point Morgan, and I mostly agree with you. But there's more to it than just a transmitting what's on the design document to your team. Maybe this is what you mean when you talk about the document as a record of decisions made, but I like to think of the doc more as a very much current, very much alive entity. I'm not saying everything in the document is up for changing, but part of it comes down reacting to what happens during actual development. Some of the feedback your team gives you, especially if most folks on your team overlap on areas (as is the case with the teeny tiny team I'm on), can be of great help. And sometimes, someone might have a killer idea that isn't going to work. Knowing how to massage their ego is a pretty important skill as well. This is just a long-winded way of saying I agree. The idea of a game designer as sort of this isolated dude in a tower, throwing scraps of direction to the hordes of programmers, artists and writers below seems outmoded, if it were ever really accurate. (And I mean hordes in the most Mongol, badass sense of the word. Love you guys!) Whether or not your project's big enough to have a dedicated producer (in which case, some of this ought to fall on their shoulders), a holistic sense of leadership's a great asset for a designer. But it's more than just communicating the document. It's also adapting: To advice from team members or the outside, to changing circumstances (be they fiscal, technological, whatever), or just making sure your programmer doesn't run out of Mt. Dew.

Besides communicating with others, a doc needs to communicate to your own future self. On all my projects I keep a diary that mutters about what I did that day and why I did it. Somedays when I'm confused or just mentally blocked, I re-read the diary to remember the direction I'm going in.

The occasional parts that read, "this module really sucks and I hate its guts RARH" is amusing to read two months after the fact. Its truth makes it amusing, plus the fact that I did in fact scale that barrier is good for later morale-boosting.