These are, well excluding China, expensive counters for an amphibious mind control unit that can be produced at 2x and a lot faster than Wolfhounds or Vultures, those air units can also get taken down pretty fast by Piranhas as well, the Soviets need a cheaper counter for the Epsilon Elite.
I'm going to answer this question before it gets asked: Making Terror Drones amphibious would seemingly pose a balance issue to the naval units, but I think this could be solved by adding some sort of repair ship for the allies, and possibly making the Stinger amphibious, seeing as Epsilon doesn't quite have any amphibious units excluding PsiCorps' marauder. Soviets already have their Repair Drone. This takes out two birds with one stone, balancing out PsiCorps amphibious Epsilon Elite, and adding some more depth to naval combat.
Edited by Protozoan, 07 January 2014 - 04:24 PM.