Let me rephrase that: Weather the Storm is not the OP talent that you claim and chars would not be willing to heavily invest in an "off class" ability for it. Gamers have no problem getting their resistances to a point where they heal from elemental damage without that talent.
The Adaptions would allow players to become immune from 1 elemental type early in the game (balancing issue) and turn useless once you start using essences. Compared to WtS having a +50% boost for 2 elements will make it harder to get everything above 100% than the current 25% vs all bonus. I would only use the Fire Adaption for mages that want to use stuff like Self Imolation early-midgame.