I feel far more users use apps that can parse and have pasted into them normal formatted text (not sure what it is on Android, guessing HTML) than markdown. I feel markdown for most people is too technical and niche.

So specifically the behavior I would love to see would be for copy mode to change nothing except allowing the user to copy text normally, just as it is originally presented.

This would also fix the problem of losing your place in the text when you toggle between text selection mode and normal mode.

The "Universal Copy" app is a partial workaround - it allows for a normal rich text selection and copy, but only works for the text that is on the screen when invoked.