What upsets me about the use of MZO's isn't just the complete and arbitrary bypass of the local planning process - it's that of the position of the Ontario government is that local planning processes are broken, an MZO does nothing to address the underlying issue.
If the Ontario government were also working collaboratively with the local planning authorities that they might improve, streamline, etc the actual "broken" parts of the system rather than just bypass things over and over with a trump card, it would be a little less infuriating.