With ad revenues drying up (Adblock, general lack to interest to ads) Google is forced to look at other avenues to make money and selling stuff to people is a great way for that.
Haven't their revenues been going up despite the CPC going down?
Their entire strategy up until these new paid-for services predicated on giving people free services (Gmail, Docs, search) under the assumption they could pay for the development and support with ads.
It seems like they're shifting to a model seen by open source software creators - free to use, but any extra features or support will cost extra.