I dont think pre-builts have any place in modelling. If people want to collect them, fine. But I put them in the same boat as Model Maniac. They are buying items to collect look at, and display, with little or no "modelling" actually done. I have spoken out previously against an RC Heng Long tank that was given a few tweaks and a coat of paint and then given gallery space in an edition of FSM. Its not modelling, at least not IMO anyway. I know there are some out there that disagree with me, so each to their own.
If I bring someone into my model room, I want to be able to point at everything on the shelves and say "I built that"- pure and simple.