Why can't free member use custom maps?

^^^What that says up there^^^

Because no one would want to purchase premium.. That;s one of premiums main thing in my opinion.

There are things that have to be acquired through commercial transactions in order to provide some financial sustainability to this game. The world of map-making is one of these features. Sorry to say, but it is very fine the way it is. Hope you can have access to some resources to buy premium and enjoy this world of map-making.