I agree.

Previously-earned points or miles should not be subject to devaluation, any more than a gift card for a department store. Ever. (In CA and other states, it is illegal for such a card to expire, no matter what it says.) Anything less just legalizes the sale of pigs in pokes.

If a particular award is no longer available as in Steve M's examples, the company should be required to substitute one of comparable value. This is not just common sense, it's the law in other areas of commerce (as when a retail store runs out of an advertised sale item).

The trouble is that legislators have not quite gotten around to the idea that points and miles are valuable things deserving many of the same protections afforded to real money. But they will.