Yeah, that's kind of weird. A day or so ago in another thread I watched a blue tell someone GOG doesn't give out discount codes for games, then I received a discount code for NWN2 via email a day or so later. LOL I already own NWN and NWN2, and have additional copies of them so a special loyalty promo is nice and all but not useful to me as I already own it. :)
Besides, these games regularly go on sale several times a year for 80% or more off no coupon required anyway.
IMHO, coupons for games in general suck and are not a feature I personally want or concern myself with. Only way I would actually use one is if I was already going to buy a game and suddenly a coupon floated into my path that made it that much cheaper on the way to the checkout or whatever. Almost never will a coupon make me buy a game I wasn't already planning on buying though, and only then if it drops the price below what the given game is normally discounted to regularly. ie: I would never use a 30% off coupon on a game that is normally discounted 80% off 3 times a year (unless the coupon was valid stacked on top of that 80% off discount, and valid during the same timeframe in which case sign me up!) :)