The opposite of love isn't hate. It's apathy. Rui-Ling's hatred just shows how much he cares for the washboard hag that helped him first get settled in Sonomachi~

And they probably dislike simple missions because it doesn't feel like there's much plot to be gotten out of it. Sorta like the difference between a fetch quest from some random NPC and a chain quest that ties in with the main storyline.