I know how you feel. My druid went with the improvement to Smite just because he casts it all the time when he solos.
Elem impairments or whatever they are called are like when the enemy casts an elemental based DoT on you or a friend. Like the wizard's DoT Freezing Whorl (or called something like that). If you get rid of it really fast, I think it's more mana efficient than healing the damage later. Some elemental attacks might have debuffs attached to them, like slowing movement or attack speed - so getting rid of them is a good idea. There are casters all over the place, and elemental attacks are reasonably common - gnoll casters use them, the "blobs" in StormHaven cast them - etc. GL