Except then you can't use those files on mobile devices or from the web UI, both of which are useful (my primary interest in dropbox, and the one thing I can't trivially accomplish on my own, is the iOS device support. The alternative is just to use Apple's iDisk, which has exactly the same risks as Dropbox, minus the cross-platform capabilities.)
I'm not sure if it's helpful to you, but I use Keypass & Dropbox to sync some encrypted data to my Android phone. It's limited but useful for storing sensitive text. There is an iPhone app: http://ikeepass.de/
I use 1password and wifi syncing. I asked them to add WebDAV support to store the bundle, which is how omnifocus does this, which is probably the most cloudiness I will accept for my password file.
