I think there are just better camps at that level, your classes get more abilities, and in general it becomes a lot more involving. A lot of the High 20's/Mid 30's camps pre-1.20 either didn't have as many enemies as you wanted or they were really annoying to kill (AOE stun from hippogryphs, AOE sleep from apkallu, for example).

Also at that point a good deal of spots you can XP at give you some nice money drops.