First: tsuwm, thank you for defining how dictionaries do their definitions--I never even realized there was a difference. I suppose one dictionary that gave both types would be too cumbersome for words...
(Oh, man, even I didn't see that one coming!)

Now: maverick, you posted:
In day to day exchanges, this means we have (according to our dispositions) to endure or enjoy a constant battle between the social forces whose interest lies in structuring, consolidating, centralising and focusing the language in use, and those whose interest is served by a freedom of expression, a decentralised and sometimes ecletic creation of personal ideolects. And that this process of ebb and flow is actually what language is centrally about.
Did you realize that you were also describing pretty much how all characteristics of society develop, as well as language? Who's going to have the power? One person?
One person and his or her cronies/family? An elected person or group? And as you so ably enlightened me, who decides who gets to even run for election? In homes, who
makes most of the decisions? All of these and more are the end result of individuals trying, by persuasion or force, to get their way.

Doesn't the U.S. have something called a language Usage Board? Does anybody know how one gets onto this board? How much influence do they have over what goes into dictionaries?

Nicholas, I am delighted to see you posting, sir! I agree with There isn't an official grammar. No-one has the power to make artificial rules, or to decide when a "rule" changes. --mostly. But haven't I read that France
enforces language? Admitted ignorance here--perhaps the law there doesn't extend to grammar.