@Hawk552
You're complaining that a demo is too short because it only lasted 15 minutes? Wow. I draw your attention to Bankshot Billiards 2 for Xbox Live Arcade. You're only allowed to play for one minute before having to restart. Don't get me wrong; I'm not criticising them - as this was probably the most influential factor in my decision to buy the game.
@kp_uparrow
Businesses change allegiances every day of the week. Advertising agencies (Valve is now included in that group) often take whatever they take can get.