Ok, well seeing as how no one has ventured an opinion, I shall say my part.
To argue, the reason consoles are often favoured over computers is simply gameplay. The reason game consoles were created i the first place was to ensure constant system specs, and ease of use when developping games. When buying a console you are buying everything (minus, of course the peripherals) you need to experience the game at its fullest. No lag, no bullshit. Plug, play and go.
I also have to say three things:
1st- The Xbox 360 was released with the XNA developper platform. Oh look, its open source! All the latest systems (and even older ones) supported homebrew and mods.
http://en.wikipedia.org/wiki/Homebrew_(video_games)
Educate yourself.
2nd- Free Online computer games? Are you serious? Many of the popular online games (think WoW style MMORPGs) charge monthly, even many free online games charge for extra content.
Ever been online with the PS3? Guess what, it's free.
3rd- Lastly after everything else, you can just install Linux or another similar OS on your console and (careful now!) it's a PC.
Who'd of thunk it?
I love my PC, I play quite a bit of online games on it, but you my friend, made me ashamed to have done so. You make real gamers sad.