I don't agree with your conclusion - it is less than what diamonds received.
You are correct in saying that that Diamonds were only ever guaranteed club access, but we were also told we would get the best available room (excluding suites).
That is no longer the case. The cert provides club access, but no suggestion whatsoever that the room will ever be anything other than what has been booked and paid for - that is far less than the Diamond offering.
I understand the rationale, but it leaves a bitter taste.