unless it's some kind of ego thing for the mapper to hear words of praise from someone else.
Maybe not necessary a kind of ego, maybe it´s a kinda of reward

I mapped a lot of time for my own satisfaction, when i was an offline user (most of my life) i hardly found somebody willing to play or check out my works. So, when i got the first feedbacks about my maps, about 8 months ago, i realized that all the employed time was worthy of it.