I think that the issue is some people don't consider Dropbox a good option to store much of anything unencrypted for sharing... This comes down to Dropbox being a U.S. company, subject to DOJ requests and gag orders, and complying with them, iirc.

I'm a little less concerned... though, I use LastPass, I used to use KeePass on dropbox, but lastpass has better integration into the browsers on the platforms I use (less good on android with chrome though, and there's the fee). I don't know that there's a better option that's as seamless for users.