I am not too sure if this has been mentioned before, but I am sure it has. I doubt I have unique thoughts about the game, let alone posts. I could not find reference to it though. I am not even sure if this is all that big of a deal to some, but man does it ever annoy the heck out of me!
If I have ventured to an area before (explorer) what is the point of blacking out my map every time I reset the instance? I am not too sure what this gains beyond frustration. I think something changed recently too, cause I remember I used to have a slightly dulled (only brightening the path that I was currently on) map stick around for a few days, then would return to all black. Now it returns to black the moment I reform.
I just think it would be good to keep that slightly dulled color map all the time (after your initial exploration), and then as you run the area, the places you have been to that run, become a bit brighter. Just keep that permanent.