Google+ Is An Identity Service
He (Eric) replied by saying that G+ was build primarily as an identity service, so fundamentally, it depends on people using their real names if they're going to build future products that leverage that information.
I blogged about identity the other day and outlined my view that every social service is hosting a part of your identity online. I listed almost ten social services that host a piece of my online identity in that post.
So I agree with Eric that Google+ is in part an identity service. But "primarily an identity service?" That's notable. Particularly in the context of what he said after that. "if they're going to build future products that leverage that information."
It begs the question of whom Google built this service for? You or them. And the answer to why you need to use your real name in the service is because they need you to. Well at least we got that out there and can deal with it.