This is key. Dropbox needs to work as a backup solution, not just as a file sharing convenience solution, because that's how users will actually use it. This potential conversation doesn't sound good:
Grandma: My computer crashed, I got a new one, but I've forgotten my dropbox password.
Dropbox: Okay, can you go get the printout when you registered saying "print this out and never lose it"?
Grandma: I didn't print that out / I lost it / the house burned down.
Dropbox: Sorry, then you're screwed because we designed our service to be usable only by those who have a deep understanding of computer security.
You're putting your files online, and there's a Web interface to access them, and you expect them to be absolutely secure - really? Encrypt them with something really solid and don't put them online, if that's your concern.
You upload your files to the cloud, and then you complain when the company hands them over to the FBI - really? Bury the files in concrete at midnight, and kill all witnesses, if that's your concern.
The guy who is agitating the whole thing - I'm changing my mind about him. He did a good job with the whole Facebook / Google debacle, but now he's coming off as an attention seeker / karma whore.
