I play games on the PC because:
* I don't have any desire to separate my gaming activities from everything else I do on the computer. On the contrary, I enjoy being able to do it all on the one system. Meanwhile, since I use my computer for more than just games, it's even easier to justify spending money on it, because the increased performance is a boon to other things, not just games. Compressing videos, for instance.
* I like being able to tweak and customize all sorts of minutia, even if it means more complexity. I also love being able to mod games; that is, apply game mods others have made, as well as make my own.
* I don't live alone, so the TV is common property, meaning I can't just up and use it whenever I like; someone else might be using it or want to use it. But my PC is just that, mine. I'm not getting in anyone's way when I use it and so don't need to negotiate.
* Gaming on the couch may be seen as a good thing by some, but from my perspective it's a big step down in the ergonomics department. When I'm gaming, I'm not sitting back, sinking into the cushions; I want to be sitting up and paying attention, and if I do that on the couch I end up hunching forward with no back support. My high-backed, adjustable office chair is far more comfortable for this sort of thing.
* Most of the games I play (first and third person shooters, action RPGs, simulations) work best with a keyboard and mouse control setup, and even those that traditionally don't, I still find comfortable with a keyboard and mouse control setup. Even if I didn't, though, I can plug in all sorts of additional controllers.
* There's great backwards compatibility. I don't have to think about 'generations'. I can play pretty much any game in my collection, even if it's ten years old or more. Some require minor tweaks to get them running right on the new hardware/OS, but most work just fine 'out of the box', and for the really old games, there's emulators. The games in my collection that I can't get to work at all are very few.
