It drives recipients to the Dropbox website.
Eg, right now I can put an image file in my /public, get the link and embed it in an img src tag without the anyone else ever having to know it's on Dropbox.
This way, I can't do that. I can make a clickable link and paste that. Then people have to click to see the picture on the Dropbox website. Where Dropbox can constructively engage them in a dynamic exciting conversation.