It would be useful to have an option to export PDF in which every page is an image file (JPG or Tiff or...). I would appreciate this because I usually send some draft to my customers and they simply open the file with some PDF editor (or Illustrator) and make changes by themselves.
To prevent this, I just export in JPG format (instead of PDF) from Indesign and then I drop the images into Acrobat and send the PDF as a draft.

We could bypass this step having this option as "Flat PDF export".

Thanks.