Well, it wouldn't hurt anyone, but I doubt it would be of much use. People usually have uber expensive items - CS eggs, beans - on their wishlists, not something that others tend to just give away to random users (if they want to give it to a friend, they can look up that person's wishlist easily). Also the other reason why people put an item on their wishlist is that they would like one, but cannot afford it right now. So even if you would like to sell it to them, they most probably wouldn't have enough TU for it (otherwise they would have already bought one, and it wouldn't be a wish).
On the other hand it might be useful for selling hard-to-sell rare items or giving away average items for junk-collectors, so I support (doubt I would ever use it though :-P).