This is completely legitimate use of a screen-space overlay (SSO) to show a logo along with data. Floweb has done a lot of work to create this service (and continue to provide it) and they should be free to label it as they please (if you don't like their service, all you have to do is turn it off).

IMHO, if a company/user spends a lot of time creating some informative KML and wants to label it either in the folder description or with a SSO, that seems fine.

The only case I can see where GE will suffer from logo-spam is if someone takes someone else's work and adds their name or SSO to the content and then try to get people to download it. As always, the logo can be turned off, even independent of the content, so you're free to define your own experience.