This is a very short suggestion,
The TDM Feature very rarely gets used, you should incorporate better rewards, such as diamond to increase farming rates, I suggest that maybe someone go do the best current way of making currency (Which I believe is farming Pig-men), killing them for 1 hour and getting an average kill count per amount of average time a TDM game lasts, and giving it 150% of the average base income of a pigman farm to promote PvP.
I think this may make a short-term fix for lacking of le pvp.