Agreed. I think G+ could beat Facebook here as they don't need to directly monetise the service and can provide more of the platform people want. Whether or not they can get to a tipping point of users however is another question.
I would also consider paying and for the reasons you mention. However, how much would you pay? i would want the service to be as good as the free alternatives. In order to drive genuine innovation and great features, the site/business would need the resources to attract the top talent. Therefore, would you be prepared to pay enough considering the competition is bankrolled by big advertisers?