One use (probably common?) of plain text compilation is to feed the tool-chain of some markup language. Markups do not rely on formattings in Scrivener but for the images they need to find the image file. Instead of keeping image files in two places (one in Scrivener and one in another folder) it would be nice to export them to some folder (configurable in the compile dialogue) .
Please note that I do not mean to create the corresponding image insertion markup as it needs specific translations for any specific markup but just to export the images to some folder.