Why do you need a capable king in a constitutional monarchy? The best king in a constitutional monarchy is a person who'd do nothing. Then this begs question of why do we still need a monarch. Furthermore, why do we need to reverse the historical development?
We need a capable king in a constitutional monarchy because from time to time, the PM and his party will come and approach the king for advise..
Is there such a thing as a king in a CM that do nothing or a President in a republic that do nothing? This is the 1st time that I heard of such a thing..
If you look at today's so called Republic of China, you will realise that the President is still as powerful as the King in an autocratic dynasty. The only difference is that a King in a autocratic dynasty can kill whoever he wants and pass his throne to his son. The President can't kill anyone he wants but if he is powerful enough, he can still pass the President seat to his son..
So in this case, why not have a CM instead.