Don't mean to be mean or harsh, but really...products don't come free. If any manufacturer were able to make a 5DII-type camera and sell it for significantly less, why wouldn't they be doing it?
Well, for starters, only Canon has the 5D2.
Partly though we are talking about an oligopoly, not a true free market. The barrier to entry in this industry is so high that there are only a few players, and all of them go by about the same playbook; charge what the market will bare with a combination of low cost entry level equipment and premium priced professional equipment, even though the manufacturing costs are pretty close across the board. They charge based off how much the bodies are worth, not on how much they cost to make.
Well, that makes my point. You are saying they "could" but "won't" I suggested they "can't," but regardless of the reason, it isn't happening and isn't likely to happen.