I have a PC. And plenty of games on it. I definitely enjoy it. Especially being able to Mod, and consolidate games on one machine And with steam be able to go between 2-3 computers to play the games I have.
That said:
Console isn't ruining PC gaming, it actually helped define it. Before consoles were big (ps2/gamecube + era) there was never a big selection of PC games beyond the small gimmicky games and some new MMO genre being born. Now? Today? So many games, look at steam, so many of those games would be for console only, if PC gaming didn't increase because of gaming overall increasing via consoles as it has. So PC gaming would still be much farther behind, if it wasn't for the consoles.
Secondly... cheap? It took a $800+ (I actually went a little bigger to $1200, but didn't need to, to play basic games) shipping and tax to create a desktop that could actually run some of the bigger games (BF3, new MMOs w/o being low fps, etc.) without many issues.
Thirdly, depends on the game if the Keyboard is better or not. I know I have a controller I hook up to my PC and use on some games because the arrows or wasd isn't good enough.
Lastly, grown-ups don't or shouldn't have that much time to game. (and by this i mean 5-10 hours a day for teens, since they don't normally have a 40+hr job and/or no school in summer) So the main target area of gamers are the pre-teens, teenagers, and college students. With consoles being cheaper and having enjoyable games, they will always choose that. (Plus none of the hassel required to upgrade hardware or even do much software updating) So consoles have and will always be the more prevalent target when it comes to gaming. (And now more recently mobile device small gaming.)
PC gaming is not going to get the attention consoles do, but PC gaming is also not being ruined by consoles, even if you for some reason believe it so, that is your opinion and probably based on your own views and evidence which isn't true with what has factually been seen over the past 5-10 years.