[throwaway59553]

>Which is, at a minimum, weird. Why would anybody want to do that (by decree, no less) is beyond me.

This is what governments and rulers have done since Mankind started building stuff. You're fixating in the legal tecnicalities like a law or executive order, but it has always been like that. Governments and rulers always set the style of public buildings.

The reason for that, is left as an exercise for the reader.