>>96864376
Also part of the reasoning seems to be that in Western Europe, education was completely tied at the hip to the church and in England, teachers were required by law to be members of the church.
Wizards are associated with sage, as are sorcerers associated with heretical religious orders like the Gnostics, Manicheists, or Baphomet worshippers. Who would adorn religion garb which would be robes.
Magic itself has its roots in basically just being considered the worship of other Gods, which is how the ancient Jews used the term magic which obviously carried over to Christianity. Any power than came from a not Jewish god was demonic and magic.
That being said it doesn't explain why religious groups throughout history traditionally wear robes. I guess the simple explanation is Roman Christianity and the fact that Romans wore robes.
But the garb of a typical Wizard doesn't exactly look Greco-Roman to me, or maybe I'm blind to the obvious ancient clothes they're clearly inspired by.