Whoever came up with the idea to have a coupon exchange probably wanted people to come into the HRH. The NGC probably stopped the promotion due to the "restricted availability... discrimination and politically incorrect, blah, blah, blah". Just make the chip available to everyone, anytime.
(My sour grapes because I didn't get to the convention last year or this year) I didn't hear of anyone having problems with the other "convention chips" from Palms, Trop, Las Vegas Club, etc...