I agree, mixing different elements is already less effective than using a single element and having effects that only enhance one element is stupid, instead of giving an enchantment that increases the status effect build up we have 4 different enchantments one for each element.
And same for damage of the specific element increased by 10%, damage increased by 10% is essentially the same thing except that one forces you to use a single element which is not a nerf of any kind since you already like having only one type of damage it is just annoying when you try to do something interesting, and fills the enchantments pool with redundant and useless effects.
I said the same thing here too: The RNG Problem, Enchantment System & Gem System “TOGETHER” (Update) But you two already know that, if you haven’t already, read the new update 