The OP is completely right: Arc damage has been gutted.
First issue is that the damage variance of the skill is insane (has always been for Lightning Skills, but now it's almost comical). The minimum damage is so low that when you happen on a streak of bad luck you can actually be doing almost zero damage across multiple uses of the skill. This is especially dangerous when you are cornered or closely chased by mobs. This issue used to be addressable by infusing the amulet with the Lightning Rod notable. But now that one has been gutted too, working only 30% of the times.
Second issue is that, in compliance with "The Vision", Arc damage has been outsourced to Infusions. When you have at least a Lightning Infusion, Arc does three times the nominal damage. Problem is that each use of Arc consumes an Infusion, even if the skill completely misses, and that generating infusions against single targets is a chore for a dedicated mono-element Lightning Sorceress/Stormweaver. It's accomplished mostly by using Orbs or by Snapping Shocked targets.
Orbs are pretty slow in generating Infusions, since they create one after the Orb expires, while Shocking a Rare or Unique target is a painful process if you are not infused, even if you take most of the Shock-chance-improving nodes on the passive tree, since Shock chance is tied to the amount of damage inflicted and the damage of the skill is low without infusions. It creates a vicious cycle that can be broken by Cursing or using Mana Tempest, two clumsy debuffing skills that are at odds with the dynamic and mobile Sorceress play style.
The result is that the single target damage of a Arc Lightning Sorceress is in a bad place right now. Bosses take forever to kill and fights that result in a DPS check are almost doomed since the start.
The class keeps getting gutted by forcing a convoluted, clumsy and unrewarding playstyle whose flow feels very off.
