You're pretty optimistic aren't you?
Ok then, I'm stumped. Explain how it is completely utterly impossible for a video game movie to be good. Thus inspiring other filmmakers to see that video game movies can be good and start giving up the funds and good directors/actors to work on it.
Not impossible, but highly improbable. Directors considered good based on their work in normal film doen't necessarily make prime candidates for video game movies. Very few will understand both the source material and fans, leading to what may have been a decent flick in its own right, but a terrible adaptation of a video game we all know and love. Unlike literature, many won't bother to sit down and view the games they're shooting as anything but cheap, mindless entertainment. They'll take the game's name and nothing more.
One problem is that these movies do inspire filmmakers, but not in the way we'd like. It's often the box office results that do the inspiring, not the faithful reproduction of the game. For one reason or another, the movies tend to do well and other hack directors/studios see the rabid fanbase as an easy way to cash in. There will be a good one eventually, but the road to it will be paved in nerd tears and rage.