For me it comes down to what the forum is for. I don't see it as a trading post and I agree that so long as we use common sense then, at our current size, we don't really need a specific feedback forum. We already have a shopping links and feedback forum and I guess that if people have something good or bad to say about another member here that would be the place to put it.
However, I do find it somewhat rude (borderline spamming) that people register and immediately head to BST to flog their wares. I quite like the idea of some kind of ambiguous note in the T & C's and a sticky in the BST stating that its for active and established members only.