It's probably because consoles are getting long in the tooth with boring & safe sequels and hardly new IPs coming out. That and a combination of PCs being cheap and even more hassle-free - which I didn't think was possible, but Microsoft, Sony and EA et al have all cocked up with their interfaces, DLC, on-disc content, and online passes which have made consoles a horrible chore to play on. PC games are headed in the opposite direction and are individually seen as much better value for money.
You have games like Team Fortress 2 for example, which gets updates for free all the time. You would have to pay if you wanted such on the 360. It's why TF2 on 360 is stuck at version 1 and will always be, because Valve doesn't agree with consoles nickle and diming you.
PC just seems like a more 'honest' platform to me and has always maintained that air whereas consoles are just a commercial, capitalist nightmare expressly ran by corporations, designed to empty your wallet while convincing you it's all good for you. People are rightly sick of it.