Unfortunately it is just not possible to view anything other than the most basic of maps on a small screen. Kindle may allow you to upload a file of 200MB in size but they then compress it and picture definition and resolution suffer accordingly. Apple only permit a maximum upload of 10MB which is half the size of the map illustrated book files, so there is the same state of affairs in existence if you reduce the quality before uploading.
I do apologise to those who complained to Amazon but you seem to have forgotten that each book is a novel, not an Atlas, the maps were to enhance the story, not the other way around.
The maps will remain in the hardcover and paperback versions of course, but until some software is invented that gives good quality graphics at a low byte count the maps will not return to the electronic books.