because,with the dlc you have:
Stalhrim Armor/weapons,which makes frost enchantments stronger.
And you have Dukaan,the frost dragon priest found in solstheim
This is a nice thing,because in the base game,frost is less valued than the other elements.
But that's just my opinion (:
EDIT:and of course,the frost spiders that you can use as a "projectile".
But there are also fire,shock and poison,I guess.