Bah, gathering is dead right now anyway until they add completely new materials and fix the drop rates. People are hammering ore and log prices down to the point where it's not worth gathering even if you want to skill up on the stuff. It's just faster to sit there buying the HQ crap the bad gatherers are selling for the same price as NQs, craft it up, pocket insane amounts and buy more cheap gathered items. I have nearly a stack of +2 walnut logs and I'd sooner NPC it than sell it in the wards for the same price as NQs. After all the buyers are my competitors in the CRP market. I can't thank the BTN enough who sold the dozens of +2/3 oak logs for 1k that helped me make my oak bow +3.
I was going to suggest something similar but then saw your solution. Probably best to just leave the current gathering areas as they are and add new ones for catalyst farming. How about let us mine catalysts in the mines, IE Nanawa and Copperbell! Put the botany ones in the Gridania dungeons and the fishing ones in the LL dungeons. Add some filler stuff to the nodes and cap that at 1 per dig/chop/fish. Give me loads of copper ores in Copperbell while they're at it, HQ copper is hard to find these days.