I'll avoid doing a Posty "disection" response in favor of something to the point: it all comes down to ownership. Why do you own when you buy a game? Do you just own the disc/cart? Is that merely an access way to content you don't own? If you buy something, aren't you free to do with it what you want?
Car dealers initially hated used car lots. They worked outside the main industry. They purchased cars off of suckers below market cost and jacked up the price to make a profit. Many people would rather buy a slightly used car at a cheaper price than the new version at the dealership across the street. The car companies fucking hated this. They said it was going to make it inefficient for them to sell new cars, and that would jack up production costs.
So what did the car industry do? They got over it and started selling used cars at their franchises. It didn't eliminate 3rd party used car dealerships, but it did sap away a whole lot of their business.
The recording industry gave way to used record stores. They hated them. They used almost the exact same arguement being used here, that costomerse didn't have the right to sell or re-sell their records, tapes, and CDs. The supreme court said if you're selling them physical media, they can do what they want with it unless you get them to agree to something otherwise (like agreeing to a EULA).
Movie companies hated movie resellers. Comic publishers hated comic book stores reselling on the used market. Publishers hated used book stores (hell, they originally hated public libraries). Name an industry that sells a permanent good, and there is probably a cottage industry that resells that good in the used market. It's the very nature of capitalism. Once a market becomes an open market, it is exceptionally hard to close it back up.
So far no industry has been destroyed by it's used market. They just have to adapt. But nobody likes to adapt their business model, especially when they're on top. Subconsciously it strikes people as defeat. It's perfectly natural to protect ones turf. Maybe Sony's DRM is their version of adapting, and maybe it will work. Maybe the industry will adapt by choosing to regulate used-game sales like the car industry has. Either way, I'm hopeful that the industry will adapt, because something bad is on the horizon. When production costs all of a sudden explode in proportion to market demand, it's usually a sign that the bubble is about to burst.
