I agree, it's a waste of screen estate and focus estate, I can't see the benefit of a minimap. I usually use imenu in Emacs so any definition is 0.1s away with a keypress
I don't tend to find horizontal screen estate to be all that useful, unless A). You have your editor massively zoomed in or B). your lines are (subjectively) too long
I dont find them massively useful, but its nice to have