Google+ decided to stop grandfathering usernames
There's a problem with your Google+ profile
It appears that the name you entered does not comply with the Google+ Names Policy.
The Names Policy requires that you use the name that you are commonly referred to in real life in your profile. Nicknames, previous names, and so on, should be entered in the Other Names section of the profile. Profiles are currently limited to individuals; we will be launching profiles for businesses and other entities later this year.
If you do not edit your name to comply with the Names Policy by September 17, 2011, your profile will be suspended: you will not be able to make full use of Google services that require an active profile, such as Google+, Buzz, Reader, and Picasa. This will not prevent you from using other Google services, like Gmail.
We understand that Google+ and its Names Policy may not be for everyone at this time. We'd be sad to see you go, but if you do choose to leave, make a copy of your Google+ data first. Then, click here to disable Google+.
An article on why they want this information: http://gigaom.com/2011/08/29/its-official-google-wants-to-own-your-online-identity/
I'm not planning to change my name.

no subject
You and I and
Facebook is largely in the same boat. LJ has paying end-users as well as advertisers (and non-paying end-users). I think at this point Dreamwidth only has paying end-users (no advertisers), although I may be misremembering.