Am about to also Qualify for Diamond and cannot truly see the point of its existence other than to signal to the Hotel that you are that little bit more special. The only Platinum gift I ever found use for were the bluetooth headphones until they glitched into Chinese and a day later the right speaker stopped working - then they were E waste.... I tell a lie, my wife uses the keyring because it carries her Oyster card (metro card) that she never uses and could just tap her phone for instead !
Oh don't you get more unusable suite night upgrades ? I've still not managed to use one as the hotels I go to always say "but sir we always give you a suite anyway why use it" or " sorry none available"