It is important to note that these "monarchial disposals" as you call them were used to get rid of monarchs that abused their powers, led their nation into wars, commited horrendus crimes, etc.

While you can take away their powers pretty easily via a law everything else, such as striping their wealth, would be punishment that needs to be justified. The Queen hasn't started any wars or genocides as far as I am aware, so how would you justify this punishment?

Her being a royal is completely legal after all!