Imaro
Legend
Right. "A rose by any other name . . ." and all that.
GH has a clear implied distinction between the central (primarily Oeridian, feudal, chivalric) regions (Furyondy, Veluna, Knights of the Hart, cities of Greyhawk, Dyvers and Verbobonc, Knights of Holy Shielding, etc) and the Oeridian/Suel east (the Great Kingdom and it satellites of current and former provinces), which I have tended to present as having a roughly Roman/Byzantine complexion.
Having a distinct order of wizards from the east that contrasts with GH's wizard's guild - and in respect of which Nyrond forms something of a cultural buffer or region of overlaps - seems to me to be consistent with that, not at odds with it. And if one wants a mysterious order of wizards with an ancient past, why make something up when I can borrow a clever idea already worked out, with a superficially neat (although, I can testify from bitter experience, painful in actual play) power-cycle mechanic?
How would it preserve the integrity of GH in any fashion to not use the moons - which are one of the more distinctive GHisms - and to instead use something like pillars? How would changing their name from WoHS make any difference to this? What is anti-GH abour having WoHS? What does that contradict in setting tone or content?
Well I do believe you are leaving out some major (arguably defining) characteristics of the WoHS, at least as they are presented in DL and those are...
1. The fact that they are the oldest of all orders
2. Any other type of wizard is considered a renegade and hunted by the order.
These being true (even if the order were named something else) would have all kinds of repercussions in Greyhawk... especially on certain members of the council of eight... but also on how magic is presented in the setting as a whole. Suddenly now in Greyhawk any wizard outside these orders is a fugitive.