but we shouldn’t change constitutions to favour the cause of the day.

This is a non-issue. Firstly, it would be a massive change to the constitution creating an entirely new level of constitutional authority, authority which would likely clash with Provincial authority. Who would handle roads, power generation, water courses, etc? This is poorly thought out. Secondly, if municipalities are to have constitutional authority, how about Native Reserves? How about rural communities? This would get messy fast.

But the point is moot. It takes a massive effort to amend the constitution and there is exactly ZERO interest among the Federal and Provincial governments to embed municipal governments into the Constitution.