PC games are getting fewer and fewer. This is due mainly to profitability. Just look at what Crysis went through. The biggest game the PC had of the year hardly sold anything due to piracy and lack of audience.
Also, it may not be an advantage to you, but for everyone else in the world, what games you're able to play tend to become important. If one system took away nearly all of the other's exclusive games, it took away a huge advantage.
PS. 360 has exclusive GTA4 DLC on the way. I'll let you know how it is.