Hey there!
Providing my years on dropbox and the fact that our main purpose is to produce books on arts, architectura & landscape, I think DB should have a native viewer, probably based on some arrangement with ISSUU or any other kinda a booklike online viewers thay allow us to showcase our work online.
The apps available charge a lot for these and I assume a big part of that is for their own cloud/storage that saves any pdf to be available when someone asks to see it. Hence I think that is not crazy to profit from our own DB Plan and save part of the money, don´t you agree?
Yours,
Nicolas.