If we're worried about theoretical abuse, the client could access all of your files because it runs as you.
You can opt out of the kernel extension? Still, you give it root to install, and it has a long history of hacking the file browser to get icon overlays... it seems weird to me that this would be a deciding factor.
I was under the impression that the kernel extension was a separate product, it's being included in the standalone Dropbox application?
You do have a point about giving it administrator privileges, the post however shows very clearly that they are abusing your trust which is enough for people to think twice before using their application..
