It could be the retailers saw a way to increase sales since no one knew if the world would end right away or slowly fade into darkness. Always on the ready to make a buck, they opted for the slow death, which would mean still more sales.
Compound that with the attendant, increasing misery and you have a formulae for success as everyone would try anything to lessen the pain. Don't forget: these guys are bean counters. They look at all the angles.
All the best,
Nonoise