The reality is that
DCL doesn't have a magic money printing press. They can't afford to just hand everyone their money back. They are looking at it from two different categories:
1) DCL is waiving their cancellation policy and allowing people with a booked cruise to postpone it for up to a year if you are worried about getting sick/quarantined/etc.
2) If DCL cancels your cruise, then you get either a full refund OR they dangle a 125%/150% or some other higher credit to compensate you for the cruise and to hope that they get to keep your money.
It is no different from the airlines right now offering to let you change your flight without a change fee, but you have to fly within a year and you are responsible for the difference in fare prices between what you previously booked and what you are booking. If the AIRLINE cancels your flight, then you get a full refund or they will dangle a lot of vouchers/credit to you to rebook to a different flight without them refunding your fare. If you rebook a flight and then the airline subsequently cancels that flight, you have no recourse against the airline because you no longer had a seat on that flight.
I fully understand people being upset that "they could have gotten a better deal if they had waited". But one of the variables that DCL might have used in deciding to suspend operations was that they were down to a certain percentage of cabins booked and now it was financially viable for them to refund those fares.
I don't blame anyone for feeling disappointed. Heck, I'm right now in a 'wait and see' mode myself because I am cruising at the end of May, there is nothing in the next 12 months that lines up well with our family schedule, and if the cruise is cancelled then my best case scenario is that I'm going to end up being refunded $8,000 in Disney Gift Cards and wondering what the @#$%! to do with them (I purchased the gift cards via BJs at between 4 and 8% off and got an extra 2% with my cash back card. I thought I was being so clever to get an extra 6-10% off of my cruise fare; now I'm wondering if I'm stuck for 18-24 months until we can get to either WDW or do another DCL cruise.). However, I can't agree with people blaming DCL for giving them the chance to rebook without penalty, taking it, and then being mad that their cruise was cancelled. If you were still willing to go on the cruise, then you shouldn't have rebooked. The people who still wanted to take that cruise have had the choice taken away from them. That is why they are getting the refund option.