There was a feature for Google Maps, on Android; where you could tell it to download and keep a local copy of some small area so it could work without net.

As I recall it worked fairly poorly (still tried to load live urls) and wanted to re-download the cache once a day or more. It was not useful for the purpose.

I always took it to be "make as many people happy with the least effort," why continue to polish a product in ways like this that few will use or ever even notice is available?

Much better to spend effort inserting local businesses into peoples driving directions. They might've wanted to stop for coffee even if they told you a different destination.