Must Google do everything?
They already pay for much of the content you see online.
Only they have the ability to say "pay $1-$3 a month, and we'll replace those ads with a thank you", and have it actually affect a significant fraction of what you see.
Google starts a lot of cool projects, it'd be neat to see other companies taking the same initiative in certain areas (I'm sure there are, I just am not well versed in that area).
There already are other similar services, like Flattr, but it becomes hard to ensure that you get a steady revenue stream by serving ads to some people and getting donations from others, and being able to turn off the ads for those people who donate.
No one seems to do any kind of pushing. You're free to not use GMail or Google Maps or whatever; people use it because it sucks less than alternatives.