I agree there are no damages here to speak of. If you don't like the revokation of the offer, you can cancel the card at no cost within a year. Your only harm was the effort you made to apply, a very minor affect on your credit scores, and disappointment.

The potential damage here to Hyatt is the negative impact on reputation to those Diamond members and potentially to the public due to the error and not making up for it. Could be otherwise handled with typical compensation, but to really make sure they keep a good reputation, they should honor the offer for those that applied, since it is really no cost to them and potentially a net positive in the end for those members. Its also a positive impact on their reputation by making good on their mistake.