Microsoft added the "briefcase folder" in Windows 98 (maybe even a '95 update). It was crappy and clunky, but the concept was basically the same. When storage prices started to fall, online lockers and backup solutions were a dime a dozen, they were just painful to use and they would kill your bandwidth. DB was successful because it was easy, nonintrusive, fairly robust and came after bandwidth stopped being a real problem for most people, but particularly original it was not.

I don't know what's the fuss about Dropbox being called boring. It's a backup service, so it's not really an insult, it's just not supposed to be exciting, or fun. It's supposed to work. It wasn't original either, but it worked seamlessly and reliably to the point where you confidently forgot about it. Would you trade that for some backup that didn't work so well, but was, yeay, more exciting? (I don't even know how you add excitement to backups... do you make it a video game? Add videos?)

It was an original, exciting, and ground breaking product in a market that had plenty of unoriginal, boring players.

See also MP3 Players and smartphones. Both markets looked boring and well-trodden until Apple blew fresh air into them.

The key to this kind of success is finding a segment that is currently niche but won't be for ever. Cloud storage, mobile internet messaging, portable MP3s, portable Internet -- all potential mass markets that were kept niche because the products in the market didn't have mass appeal.

There were tons of online storage systems before dropbox, they just had clunkly interfaces.

Don't know why you're being downvoted; Dropbox was very original in that it was

1/ completely platform-agnostic

2/ completely automatic

None of the previous attempts at this were even remotely addressing those two (simple) concepts... and they still aren't!!