New Method to Promote Custom Maps

Why don't you allow map makers to pay protocoins to make their maps avaliable for non-premium players, like for example:
Map Maker X pays 300 protocoins to make Map Y playable without subscription for 1 year.

This will make the game funnier and maps maker will pay more effort on their maps as their maps will be played more often.

That's already a thing. You can make maps playable when you promote them...