This seems like a good time to resurface the worlds best Quora answer, by Michael Wolfe. Answering “Why is Dropbox more popular than other tools with similar functionality?”: Well, let's take a step back and think about the sync problem and what the ideal solution for it would do: There would be a folder. You'd put your stuff in it. It would sync. They built that. Why didn't anyone else build that? I have no idea. "B…
Even though I agree with the conclusion, because I think files & folders is one of the very few computing interface metaphors that has proven itself, I disagree with the reasoning here. Maybe that's too many years of hearing similar language in arguments from Linux Desktop evangelists.
I think the real reason it works so well is not that people don't want that other stuff, but that it is straight-forward for users to architect solutions to a lot of those other things on top of a simple folder-wat-syncs because they can very easily wrap their head around how a folder-wat-syncs will behave. Case in point: many people, like myself, use Dropbox as a password store by keeping a KeePass database in it. For a short time when a buddy and I had the fool notion to start a business, we coordinated and kept track of things through documents on Dropbox. Simple tools one can combine to perform complex tasks; sound familiar?