-More .22s than any other caliber around
-Can't reload .22s
-Trying to make a profit
-In most places(not including places like Tom just mentioned) people are stupid and act like .22 will never be available again
-its usually the cheapest ammo and therefore the easiest to stock up on
Thats a few reasons, but who really knows? IMHO, it will be fall, maybe even Christmas, before we see ammo back available like it was before. Notice I said available, who knows if prices will ever come back