you can't have too much security, ever. especially not when loads of personal files and potential sensitive data are getting stored under said security.
Security is not free (as in beer); there exists some level of security that costs $X. If the value of the thing you are protecting behind that security is $Y, then for every X such that X > Y, your security level is a luxury.
Furthermore, there is another number Z, that represents your total operational costs $Z. You could argue that for every X/Z > 0.1^T, where T is an arbitrary threashold, X is a significant cost to the organization and you cannot affort to take that luxury without risking bankrupcy.
So, yeah, Drobox stores loads of personal files... but people with real secrets to keep should know not to rely on freemium services.
