As a Prime member, I think it would totally be worth complaining about a promotion disappearing for non-Prime members. If absolutely nothing else, it means the people who would buy games during E3 now get a significantly worse deal because they'll have to pay $80 for the privilege. Or in other words, it's a discount that only kicks in after you've purchased five full-price games. Buy five, get 20% off your subsequent games. Not a particularly compelling proposition.
Yeah, there are other benefits to Prime, and yeah, you don't have to wait for E3 anymore, and yeah, you can wait until a game actually releases, see if it's good, and then buy with the 20% discount. But for someone who is completely uninterested in those benefits, or someone who doesn't want to pay the additional fee on principle, it's hard to argue the service hasn't gotten worse. Moreover, it also means Best Buy has less incentive to compete with their own deal, since they don't have a paid-membership option to push.
