Why extract brew? Just go buy some already made by a professional brewery and save all kinds of time and trouble.
Well, Mr. T, I'ma gonna have to disagree. Extract brewing is still doing at least part of it yourself and giving you some control over the procedure, as well as the satisfaction of knowing you did it yourself. Of course, AG takes that a step further, but I can recall how proud my friends and I were of the extract beers we made and how well many of them turned out. Maybe some of you "AG only" guys need to go back and make an extract batch again and challenge yourselves to see how well you can do it.
That's actually the point I was trying to make, albeit poorly done
My answer to "why extract brew" is the control, cost, satisfaction, etc... and everything good everybody else has submitted.
Once that is answered in your mind and all the benefits are rationalized, then the OP has the answer to his question "Why go all grain?" More of the same just up a notch.
"Just go buy some already made by a professional brewery and save all kinds of time and trouble." was just a smarta$$ way of saying think about why you had rather brew than buy.
<slip back under the rock>