Essences are not small optional bonuses. It's your left hand to progress. Without essences or crystals, you stagnate, that's clear.
Crystals are forged to boost the weight of your weapons and armor, which raises your stats. Essences, you put them in your Abyss Artifacts to unlock crazy skills or rebuild your builds. From level 15, you really need them if you don't want to lag behind.
In a nutshell: accumulate this hardware, or you'll end up stuck.




