The glass half-full side to this is that you get 12 less errors than www.google.com.
I'm not the best person to ask about this, - I see W3C validation as something to continually aspire to but not to be a slave to. My order of things is to get my page working in all browsers first, looking and functioning the way I want it to second, and then clean up what I can last.
W3C is more about creating a unified set of standards that both browsers and designers can work towards to make things easier, than it is to dictate what must already be. So I think it's good to test your page, and correct what you can according to the advice, but the thing is to get it working in all browsers first.