Originally Posted by 1flyer

It has nothing to do with reasonable. It is a simple fact that your real income has fallen. Suppose your income in euro is 100. When an apple as well as a banana cost 1€ each, you can buy 100 pieces of fruit (in whatever composition of apples and bananas you desire). Once the price of the banana rises to 2€, the space within which you can decide gets smaller. There is a negative income effect. For instance, if you buy ten bananas, you can no longer afford 90 apples as well but only 80.

Whether the decisions you make are reasonable or not, it is simply a fact that there are fewer bundles of apples and bananas that you can feasibly buy given your income.

The analogy still carries over to IHG points. It is unambiguous that the devaluation makes you worse off. (Unless, of course, we're in the extreme case that you don't desire any award nights except those made available as point breaks. But that seems a quite far-fetched scenario.)