There have been other online extended attribute databases. The biggest I can think of is MoodLogic, which, I think, cost money (or earn credits by submitting data?). I read a lot of bad user comments about it and I think it folded, after taking the subscription fees from many users without providing the updates or service that they promised.

The usual, get money involved and you're bound to make someone upset. So, keep it free, and you can do whatever you want (HA, not really, but you can always try to make that claim). Someday......