I always have a lot of loot and sometimes need another salvage kit when I finish a dungeon. Sometimes I like to do more than one dungeon run at a time, so it would be very convenient to have a merchant right outside of every dungeon, where loot could be sold and salvage kits and other stuff could be bought. Otherwise, I occasionally have to go all the way back to town and then come back to the dungeon entrance again, which is very inconvenient.