On a philosophical level;)
I mean, I thought stuff like Steam, Battlenet, etc. are like the very essence of gaming.. for those who like to play games while sitting in front of an actual PC. Not just the controller, but also having keyboard and mouse are part of the charm of PC gaming. That and the fact your kit is only as old as you want it to be (unlike a console locked to its specs for years of its lifecycle), so the Crysis maniacs have something to talk about all the time.
So what they do instead they get rid of the whole "PC-ness" of Steam (or do they leave the option to upgrade components?).
Interesting. Will we see StarCraft 2 for XBox360 soon as well (would be hilarious to see some micro champions kicking the fuck out of controllers)?
But then again, browser games of all sorts, shapes and sizes are totally legit now, while it was a fairly laughable concept not so long ago..