This is a fabulous idea. I too am happy to have the Design Hotels even if they don't have special Platinum recognition. The ability to earn (and spend) points makes it worth it. Of course, if some Design Hotels begin recognizing Plats that will make them even more desirable.
So far we have only had 2 Design Hotel experiences- the Gramercy Park Hotel in NYC and the Palazzina G in Venice. Both hotels were wonderful with stunning rooms and fabulous locations.
In both cases we had splurged for special Suites so we weren't expecting any upgrade. There really didn't seem to be any acknowledgement at either hotel that we were Platinum guests.
We are really looking forward to exploring more Design Hotels.