I can't get behind giving PL players WCS points. PL is it's own separate entity. the teams choose weather or not they want their players to go. the players choose if they want to be on a PL team. If players want to play in WCS and PL they need to structure that into their contracts with their PL teams. The best players in the world are probably going to have more bargaining power to do this. We can look to other sports for examples. In soccer (football) teams allow players to leave to compete in national team games. This is because most players structure that into their contracts and because the different leagues know that it promotes their league to show they have the best players on a world stage.
We can all make a very strong case that PL players are some of the best in the world. However because they don't play the best outside of the PL you can't say for sure. It is up to PL to allow their best players to compete in the WCS. Not only would it grow the WCS it would grow the PL as it solidifies without a doubt how good their players are.
It is up to the PL teams to allow for this, if they decide to not allow their players to travel you should not reward them.