One reason i can think of not doing so is stripping directory for all use cases will put all saved files under /sdcard . As of now they are getting saved in correct sub folder with the original image with a version suffixed to it. 

To answer your other query in https://bugzilla.mozilla.org/show_bug.cgi?id=992426#c12, we are checking for file does not exist in the same folder before saving and we put filename_version if it exist e.g. test_1.jpg