DoW/DoM selling their services is no different than a crafter selling their services.
if someone cant/wont do a dungeon for whatever reason and they have the money, who cares. its smart business.

now if the person bought gold to afford that service they are the only one in the wrong.

rmt is against the eula
pc's playing the game and exchanging gil between themselves is not.

tl/dr If im follwing the rules i can give MY gil to whoever for whatever i want. ^^