There are articles on the subject, I can't recall them off the top of my head. The gist of it is that Dropbox is more than just cloud storage. They've put an unbelievable amount of work into the syncing client itself on all platforms so it's really robust, very cross platform, while at the same time uniquely tailored to each platform and completely seamless in operation.
And anyone can clone it, which is the point. If Google decides to launch Gdrive, it would dwarf Dropbox instantly. Whereas even if you were given all of Facebook's hardware and software and staff, but not user accounts, you would have a hard time competing with Facebook.
I'm not sure about that. Google Music's sync client is horrendous, as were Google Desktop and Gmail Notifier. I wouldn't trust Google to be able to make a client on par with that of Dropbox. (Remember, Dropbox engineers actually reverse engineered the Finder and performed code injection in early versions to get the user experience they wanted.)
A singular devotion to UX is not something that can be duplicated given "the right amount of engineering resources". (jrockway's thinking is totally emblematic of Google and Microsoft.) It requires the right, most product-focused people in charge.
