If you think about this logically then I see two major plotholes in this theory: 1. Xur - Xur has already sold three of the four "most prized" exotics. Why bring a concept like Xur into a game you are trying to control? Chaos theory at its finest. If anything his mere presence completely undermines the pinky and the brain-esque weapon flow control you are referring to. 2. They would have had to know before the game was released exactly what weapons were going to be prized over others. This is the major flaw. Who knows exactly how a community is going to react to a variable until you introduce a variable? Bungie are total novices into the MMO market therefore unless they spent some serious coin on psychologists and did some market research they'd be taking a pretty big punt. I can't see a company spending millions just to annoy the heck out of its player base. Some people just get lucky and others don't. Look at the lottery!