Actually, the reason it won't happen is because of the realities of game development, not for the reasons some of you imagine. No matter how much you exaggerate downgrades or complain it's not going to change those realities. At best you might encourage devs to simply stop showing their games until much closer to release, but I don't see how that benefits anyone.
Think about it, nearly every big game these days has some downgrade claims directed at it. Everything from Infamous Second Son and Assassin's Creed Unity to Uncharted 4 and The Witcher 3. Some of these games are made by some of the most well-regarded developers in the industry. So what's more likely?: that all these devs are really incompetent, lying douchebags or that some gamers simply don't understand the realities of game development and also tend to be very poor judges of game graphics?