In my opinion, paying developers before a product is finished is likely the biggest portion of the problem. If a game publisher can make most of their game sales from pre-orders and day one sales, before the bad press kicks in and warns away their revenue stream on bad products, why should they care about the state their games are in when they launch, more than they care about the product release into the marketplace itself? As things currently stand, publishers have a monetary incentive to release their products once projected sales figures have been met through pre-orders and day one sales expectations, not finish them, and since refunds on open software products are hard to come by, it's hard to get satisfaction from a software publisher on a bad product.
Consumers are taking away the publisher's incentive to produce good products, and instead, are rewarding them for releasing titles earlier, before they are ready.