It would be, to a degree, but Wiz is already squishy and has low armor, so physical is still a huge threat, and honestly the most common damage type. Any Wizard main knows how easily poison will SHRED even decently-built Wizards, and archers of any type can really humble a Wiz main. No matter what build I’m playing, Bogon Trappers are one of the most dangerous enemies as a Wiz. Plus, those enemies that burst into poison clouds on death remain a huge threat when killed in large quantities.
While immunity to 4 elements is pretty OP, almost every enemy in the game can deal physical damage, so it’s not like any given (at-level) rift becomes trivialized by this. The Wiz would still very easily be able to be OHKOed without proper damage reduction.
EDIT: Like, for example, I’m doing a GR123 right now and despite this build giving immunity to elements, I’m dying INSTANTANEOUSLY from any element I’m hit with. Mortar, Acane, Fire Chains, Frozen - All elements I am theoretically immune to and yet if any of these even graze my pinky toe, I’m OHKOed even with max Magic Weapon - Deflection stacks and my Galvanizing Ward in place. Maybe if it could Teleport more freely like the Firebird set, it’d be less troublesome, but cooling down Teleport fast enough requires enough attack speed that it’d drain resource below the 90% needed for Aquila’s Cuirass to remain in effect. So the Teleport would still be relatively slow AND I lose the 50% damage reduction. The immunity just never seems to save me when it’s needed. I’ll be standing on a frozen mine when it spawns, not be taking damage for that half a second, and the moment I’m not immune to cold, dead.