The trick with that, if you have multiple cards, is getting the right offer to the right card. Yeah, it probably doesn't matter 95% of the time with offers you know you won't use. But if you have two or three (or more) cards eligible for Amex Offers, you probably don't want to auto-accept a restaurant or grocery offer on the Platinum card when you have a Gold (unless the Gold isn't getting the offer).

As an aside, it would also be useful to be able to look up a merchant and find out which card you saved the offer to.