I mean, pretty much every resource but your own time and guild reputation is pointless (and even that loses it's use for most of them after a while), and you are even rewarded for just letting time fly by. There is no point to doing any slave request as you can always just skip a week ahead and re-roll the requests.
That being said, a big buff to reputation or rare resources (things you can't just farm, like mythic leather or monster drops) for these quests would be way better than any gold increase.