I work for my clients and not for my suppliers and as such my clients pay my salary.
I agree with you an agent should work for their clients, not the cruise lines. HOWEVER, the commission IS your salary, and in my view you shouldn't be charging your clients over and above the amount of commission you earn by representing your clients.
Over the years I've heard the mantra of we "provide service" or "we give our clients value ",so we don't discount, and we charge extra fees.
I've been around the industry long enough to know there are plenty of great agents who provide BOTH without charging extra for the priviledge of working with them.
I don't think travel agents should work for nothing, but I absolutely don't go along with the view that an agent can only provide good service if they are charging all sorts of additional fees.