This. You'll rarely get from Gamestop or another retailer anything close to what you could get just selling it on Craigslist or even eBay (which makes sense -- they need to resell your stuff to someone else at a profit and have serious overhead to cover). Of course you'll have the hassle of coordinating with a buyer, and will face competition from the 1000s of other people trying to sell their XBox 360 and PS3 setups to upgrade to the new consoles. But you should come out with a bit more money (and in cash, not store credit) this way.

I'd largely blame piracy for ruining PC gaming. Once consoles were powerful enough to play the bigger-budget type games that used to run only on PCs, a developer would be foolish to focus on the PC (where a huge fraction of the userbase will pirate the game) vs a console (where, in exchange for a fee to Microsoft or Sony, you get the relatively strong copy-protection scheme of a console to protect your development investment).