It's also important to look at all the competitors dropbox had and currently have.. and still, they're extremely successful. So, basically, they found a nice problem to solve and solve it. The goal there wasn't to be able to sync all possible folders.. just one little folder where anyone would put their stuff inside and that'd just work.
And, more importantly, it makes me thing about what tools we use every day that the no-techy don't know about.
In my opinion, there's really something to do with the terminal. It's such a crazy productivity boost and, if implemented correctly, might be way more intuitive. For instance, everyone knows people that are scared by all the buttons/windows/popup dialog/etc. For us, geeks, it's so easy.. we see the screen and automatically abstract everything and focus on right part; but for them, it's impossible to abstract so many new things at once.
A terminal, IA based, could make it so easy for no-geek to use a computer. Obviously, I'm not talking about BASH but something that could pretty much understand beginners commands. I.e send a email to bob.. which could guide the user through various questions.
Yeah, it's probably stupid. But hell, I'm sure they're hundreds of product as useful as Dropbox.. we just have to think about it.