What about those tags already in western tech that re-establish Byzantium with the decision all greek orthodox get? Should they get the unique government and be stuck with it, since they cannot and need not westernize?
A common strategy is to form Byzantium with another tag, mostly western tech, strong in naval power, such as Venice or Aragon.
Point is, I'd rather have an expanded set of DHE dealing with the challenges a resurgent Byzantium would have faced (for example, rivalry with Venice, trade profits waning due to the discovery of a route around Africa, modernization of the state). Those are, of course, not easy and quick changes, while an unique government would indeed be both easy and quick.