Why do XBLA games not have to deal with this restriction? Personally, I never decided that I wanted to purchase a game after only playing it for a few minutes. I need more time. I think Microsoft are shooting themselves in the foot, because there are gamers out that like me, absolutely despise timed demos. Nothing annoys me more than a pop up screen asking me to buy the game. If I want to buy a product, I go to you and buy it. If you try to force it on me, I see that as an act of desperation and that you possibly have doubt in your own product.
At least provide us with some options. Like if we have multiplayer and we limit that, or we limit some game modes, that should be more than enough for a good trial restriction. We need to have our trial modes approved by a real person anyways. Do we also need this automatic limitation too?