DCL's price is worth it to sufficient people to fill their ships with enough people to make money and keep operating. In times of economic stress of public fear, DCL has found ways to fill their ships using various discounts. If you watch the boards you will notice that cruise lines will raise fares, until just before the cruise and then offer targeted discounts to fill the last bunch of cabins.
If Disney was having problems filling ships they would be running these constant sales I see from the other cruise lines (free drink packages, free specialty dining, etc.).
What you are talking about is Disney lowering it's profits to make it more accessible to those unwilling to pay their price. If and when Disney has more ships and cannot fill them or has a unpopular itineraries they will adjust their pricing downward. Until then these are the prices.