Cedric: Well, again, everything should be prefaced with 'This is just my opinion...', but I'd like to think I have a well considered, experienced opinion. However, if not knowing the rules is not causing a problem in your campaign, more power to you. Don't fix what isn't broken.
But, I'd still say that in general, the DM needs to be the person at the table with the best working knowledge of the rules.
That is not to say that this is the only trait of a qualified DM. BA can be as rules fluent as you want, but if he can't personify, tell a story, be creative, draw upon a sufficiently broad ammount of knowledge to keep his world believable, keep his ego out of the game, and put in the work required to make it come alive he isn't going to make much of a DM.
"Also, how do you handle running something new? By your definition of what a DM needs to know running something new could never happen."
Why? When did I say that nothing new could ever happen? Is this the fabled Hackmaster game with a random table to consult for everything that has ever happened? However, while you want to introduce new things all the time, you want to keep the introduction of new rules mechanics to a minimum. Inventing a new rules mechanic for everything is exactly the problem with a system like 1st ed. D&D. I know, because I used to run 1st ed. D&D and every new thing was a new off the cuff mechanic (and every Dragon article was filled with new ones, and every new monster had its own unique mechanics). Even then though, players could pretty much feel comfortable that what I was going to ask for would fall into several familiar categories: save vs. paralyzation (reflex save mechanic), ability check (skill check mechanic), or opposed roll (basically unchanged in 3rd edition). Third edition just tightens that up, so that rulewise, every new thing is basically a special application of existing rules - which is what you want in a system.
"The rules do not matter nearly as much as the game does."
Sure. The idea here is to seamlessly use the rules. If you don't know the rules, it interupts the flow of the story. This is especially when you rule one way when the player was expecting you to rule otherwise and had every reason (under the rules) to expect you too.
"Where I can, I try to discourage people from reshaping D&D into a WarGame."
Agreed, which is one of the reason I don't want minitures on the table until it is an absolute necessity. Nothing is worse for killing role play than having players acting in third person through some little lead minature. The best role players start out RPing without knowing the rules, which is the way I prefer to train them. But the same is not true for DMs. DM's gotta know the rules. In fact, I've found as 'god', DM's need to know EVERYTHING. Everything in it is your creation, and it only is going to be as detailed as your knowledge is. If you don't have a head for trivia (how are medieval swords made, how is _anything_ made, what is the proper form of a address to a Duke, how much does granite way per cubic foot, what kind of sails are used on a sloop, how much can a canoe carry before swamping, what is the proper term for _anything_, what does a limestone cave actually look like, etc.) then you either don't need to be behind the screen, or you need to be cultivating your knowledge.
