The whole thing about Dropbox is that just works. Files are files, folders are folders, if I move them about they move, etc. The only problem with Dropbox and Office is how Office locks the files so they're only synced after I close the Office program, not after every Ctrl+S. Fix that, and it's integrated.
The whole "save in the cloud" nonsense that desktop Office programs have these days feels like a mistake. I can understand how with iOS's "no files" design, this is the only way forward, but on desktop? Please let it stop.