Aside a few lapises and a few gear items there is simply nothing you can farm that interests a lvl 70 player who wants to build pvp gear. For a healthy demand/supply economy, there is not enough demand for in-game obtained items.
Agreed. Most 70s feel that they don't have much to do except pvp.
Farm places for 70s:
1. ROTCO: difficult even if there are many people. Cool-down time.
2. Queen Venus: 10% dropping rate? takes 20 to 40 min? no way.
3. OI: ...lvl 6 lapis? lvl 60s can do OI too in the past with the help of a few more people.
4. CS: now a pvp place between Light and Dark
5. SC: no 70 will farm there for the cheap lvl 6 debuff from mobs. And SC boss has also become pvp region.