The problem with energy drain (and WHM lilies) is that they're exclusive to SCH and WHM, while the other healers get ridiculous amounts of oGCD's for free. Optimizing lilies or maxing ED uses only results in output that's roughly on par with AST/SGE. Therefore ED or Misery isn't a reward, but becomes a penalty or tax that you're forced to try and mitigate simply to keep up.
ED could be good design, but not in a world where two healers get the same advantages for free.