Insane spell mana cost

Logged on my arc sorceress to see how the changes effected her, es being virtually halved and damage was shrunk to 1/5th of what it used to be. I can actually get behind the change because i admit there was a bit too much damage. To my shock arc went from being around 1.2k mana per cast all the way up to 3.4k mana per cast. Orb of storms being scaled virtually the same. I genuinely do not understand for an insane increase to mana cost while destroying the dps that hard i cannot rationalize this other than you dont want us playing that archetype.

Taking off the +3 skill gem only reduced the mana cost by only a 300-400 mana,i dont see how its even possible to fix the mana cost with out not using arch mage. Why even have arch mage in the game because my simple brain can't even see how its possible to get enough mana to sustain that "dps".