Too bad, I was considering them for a 4 day West Coast repositioning cruise booked last minute if the price dropped below my admittedly low target. Now, I'll have to look at other lines. If this becomes an industry practice then I'll look to other land based vacations.
Vacation dollars are fungible and can be spent on other interests but sailing with empty cabins is revenue lost forever. The passengers can play this game just as well as the cruise lines.
As far as last minute deals over New Years flexibility is the key but don't expect anything really low.
Check out cruiseplum for last minute deals. They aren't a travel agent just an info service.