Looks like each credit a member had was worth 7 points regardless of their member level. Those with 1-7 credits then got 1 bonus point added. Those with 8 or 9 credits got 3 bonus points added. Those with 10 or more credits got 13 bonus points added.
Hence, some higher end platinum members went to emerald level. It appears nobody got bumped from diamond to diamond plus.
100% will never be happy when something is changed. I'm sure RCI assigned a risk factor to the changes and knew some might get mad enough to walk away, but they feel that in the end the company will come out ahead. None of these loyalty programs (cruise, airline, hotel, grocery store chain) are meant to be a show of altruism for the products users.