I have no facebook account, I don't want one and I certainly don't create one to use your version of etherpad. No offense, just think about it...
Would you login using a Gmail account? A Twitter account?
I think the facebook integration is a waste of your development time. If you keep it, keep it only for the easy population of pic+email+username. Also, get rid of login if the pad is truly open to everyone. I'll keep using one of those other etherpad instances, since there's not much facebook integration gives me over a stock instance.
Apologies if I was a bit harsh.
I dropped GMail about a year and a half ago. If any services I was using required it to log in, I would have had to drop them, too. I think it's mostly because I know a lot of programmers, but I do know a large number of Facebook "conscientious objectors" (myself included) who can't log in to things that require Facebook.
It's really nice to have services like this self-contained (as long as it makes sense; Twitpic, for example, would be less useful if it had no hooks into Twitter). I can pick the service up and if I don't like it, put it back down. And if I drop some account elsewhere or just change accounts, nothing depends on me having it to log in.
With all respect, hackpad has a fraction of the features of the other etherpad forks (including the original etherpad). That's not necessarily a bad thing, but nor does it give me a reason to use it over say piratepad.
