I get why they do it, obviously doesn't mean that it's right. The idea below I think would actually be pretty rock solid, but I think in the interest of them selling discs (or soon, digital distribution copies), it won't happen:

The idea? Why couldn't a high powered video game system output two HDMI ports, one would be player 1, and one would be player 2. Some games could even take advantage of this "multi-screen" technology for some really cool experiences. Basically, Nintendo DS on the big screen.

It'll never happen ... but it sounds like it would be fun!