Im not disagreeing with this BUT i think you missed the point that there is a LOT of content out there already thats underused.
Swamp caves. Retarded damage. not fun.
Bat Caves. Retarded damage. Not alot of fun but at least the bq bones are a reward.
Aparation cave. UMMMMMMMMMMMMMMMM. a sword?
Graves. Great fun. Can be done as a team of two with the antipoison being spammed on a tank to keep him up but not so great for a spy/pe/apu. also the VK vest drops.
Juggernaut Facility. I think i have only ever been there once. Not much point if not doing the Juggernaut quest. Great place though.
Tweaking some of these encounters and actually making them viable and worthwhile doing (make the drugs recyclable from the swamp shaman could be one way of encouraging people to those caves as well as fixing the damage so they are doable) and you provide a LOT more content that doesnt need to be mapped out etc.