You're assuming the proprietary format could only possibly be more expensive, and assuming there would only be one vendor. Furthermore you are assuming that blu-ray support precludes other formats costing less, which is wrong.
Finally you are refusing to consider factors OTHER than cost.
A flashy-first game is awesome when it comes out. A great-first game is awesome forever.
Plus, just for the hell of it: Kelly Brook at the 2008 BAFTAs








