The old adage in consumer pricing applies to cruises as to virtually everything else: “You may - or may not - always get what you pay for, but you surely will never get more than you pay for”.
As long as price, not product, is the governing factor, the cruise lines will continue to hold down prices by trimming the quality of the product—- such trimming is effected by reducing service, quality of food served, itineraries (including ports), and even space per passenger. The continuing willingness of mass market cruisers to accept such trimming guarantees the continued degradation of the experience.
Perhaps the ultimate seagoing bargain is that offered by the Staten Island ferry: it costs nothing. Of course, it does not really go anywhere, or offer good food or entertainment - but it does give you a ride over water on a metal vessel.