I think it's a good policy. Some people may think twice about leaving their towels on lounge chairs for a long period of time. If no one is at the towel exchange area (which is very seldom) I just take my towel to my room. If I'm with a small group, just one person gets the towels for the group - the same person has to return the towels. You don't have to use your seapass card just to exchange a wet towel for a dry one. How simple can it get?