why is it that you need to vote for the next daily free design? could somebody please explain.

Of course you can get your designs free if you have a membership. Even then we vote when LETVIA post under Voting Requests. That is a way of helping other Cuties to get designs that they either missed or would like to have. It becomes a combined effort.
WELCOME TO CUTE

The one that gets the most votes is the one that is offered for free. It changes every day. So, voting has to be done each day.