Having a PC does not mean having a PC that one can or will game on. You person with the average Dell or HP with no video card and a CPU and RAM that are just barely sufficient for most recent games won't be playing the newest game releases on it. They see it as just an Internet and multimedia machine. Most people with gaming consoles don't also have PCs like that. Consoles all have the same hardware.
Your right Zed i used the wrong expression there I should have said this probably:
Maybe from there point of view, there are people who own both an console and a powerfull enough PC, and to maximize there sales they release it first on the console (and since the majority with a console & a powerfull enough PC wouldnt wait for the PC version to be out) they will have a better sale on just the console.
Then after a while they release it on the PC with some improvements (as i said in my previous post, like Devil may Cry 4 it had an extra options on the PC). Of course some of those who enjoyed it on the console and have a powerfull enough PC to play the game will buy it again this time on the PC. Also those without a console but with a powerfull enough PC that waited for the game, or are going to want and try the game will buy it.
Now this is just my opinion i dont say they are thinking this way, but it just seems the best Marketing Scheme to get as much cash as possible, also blaming it on piracy distracts everyone from this point of view.