There is a HUGE financial incentive to force people into using their real names.
"Financial incentive" is not, or rather, should not be a valid argument, ever. Especially not for infringing on fundamental principles of personal rights and liberties.
We (as in, the privacy/anonymity advocates) have always known that Google/Facebook wants to profit. What we question is why that is any justification for the shit they are pulling. Has capitalism really clouded most people's minds this much?
Besides, there have been non-intrusive ways to implement Like/+1 Buttons. heise.de for example did. You might remember what Facebook did - threaten to sue. With reasons that I cannot describe as anything but bullshit.
Heise.de only "fixed" generalized tracking, not the single-sign-on/unique-ID problem, which is the real root of the issue: as soon as a website, or Disqus, let you log on with your FB/G+ identity, you're back to square one.