Devaluation not unexpected, though it does seem worse than expected and obviously a big blow to relatively affordable higher end redemptions which were one of Hyatt's real strengths.
Everyone should assess whether Hyatt continues to work for them, just as they've presumably done as Hilton and Marriott have mercilessly devalued their points over the past five years.
All the handwringing seems a bit pointless, as it is extremely unlikely Hyatt would roll this back.