It exists solely for the transition - if Flickr's the only source for these photos, then (assuming you have a sufficiently hefty Dropbox account) this tool will at least get those files safely back in your hands. What you do with them afterwards is of course up to you, but this wasn't intended to solve a migration problem.
The photo-sharing site I made, OurDoings, will pull photos from a shared Dropbox folder and delete them after posting, allowing you not to be limited by your Dropbox quota. Hopefully someday lots of photo-sharing sites will have this option.