I think that as long as people are willing to provide maps for free (and there are many such generous souls right here) then there will be requests for free maps. Sometimes people just fancy it, or are having some trouble with inspiration for maps of their own. And there are people for whom that $10 or $20 is a lot. Also, as soon as you make it a paid commission, for however little that may be, the relationship between the person asking for the map and the person providing it changes. I think they are two different things.