I think I just don't share the same fears as you do, or I misunderstand your comment. If Google gave me a 5-page questionnaire with drop down menus and fields to fill about me, and what I like, I'd want to fill it in. In my experience systems that know more about me can always produce a better and more targeted experience. It's a no brainer.
I'm all for services making money. It's not an insignificant amount of money to run something like Google+. I'm just saying there's a place for everything. I don't think using it as a blogging platform is sustainable in the long term IMHO.
Unless Google learns that you don't like to buy things and so stops wasting everyone's time and money.