I think it wasn't cool of Blizzard to make Armageddon the only elemental skills that can be cast in shapeshifted form. Doing so has thrown away a couple of build ideas that would have been very cool and possibly more effective.
Some builds have capitalized on the sole Armagedoon/Shifting capability, like the Earth Shifter Druid. But Armageddon, despite the higher damage possible, is kind of a lousy skill compared with Fissure or Volcano. I would rather use those as a Werewolf or Werebear.
What could have been the idea behind it? Preventing overpowered builds? I doubt that would be the case--the hammerdin remains the stand-alone overpowered build in the whole game.
As for the wind side of the skill tree, I don't think those are viable with a shifting build to begin with, because they all pretty much require mutual syngery maxing for viability. So it's mostly a gripe with the fire skills. Anyway, it is a shame.