MS is making money on the 360 in games,online and movies,so they decide to support the 360 and not the Pc...plus the Pc is very easy to pirate games for,so the choice was obvious.
Age of Empires III was huge on the PC, but it only sold two million copies. There were probably a lot more copies of that game pirated than sold.
On the console, because pirating is so difficult, a good game will easily sale two million copies. A huge game like Halo or Call of Duty will sale several million copies.
Pirates killed PC gaming, or atleast games that dont require a subscription.
I never played AoE3, but I heard that while it was a good game, it was nowhere near the awesomeness of it's antecessor. It was just good. But AoE3 still had 2 expansions though, which made more money for the developers since PC gamers tend to buy expansions for games they enjoy.
About piracy, you are crazy. Have you seen the PC games lineup this year? It totally crushes any console, hell maybe even beats all consoles lineups combined.
PC is evolving to online, and Digital Distribution brings higher profit margin, neverending shelf space and features that cannot be pirated. Steam is awesome by the way.