Why using Chrome OS makes sense. And why not.

Chrome OS´premise is simple. As Google sum it up themselves:
“Google Chrome running within a new windowing system on top of a Linux kernel.”

As people use more and more webbased apps, they use their computer´s operating system less and less, so it makes less and less sense to pay for said operating system. Especially if it´s a piece of crap like windows and your money is going straight into the Bill and Melinda Gates foundation.

Somehow that irks me. So yes, I´d love a free, webbased OS that has moved with the times (Vista anyone? Did I say crap? That´s an insult to poo!)
Now here´s the thing that worries me:
So how is Google making money off this? Will there be ever more intrusive ads, maybe even surrounding your documents, like they do now in Gmail? Or is it simply a world domination thing? Will we one day only be able to buy computers that use Google software? Where does it all end?