The video-games movies are only pointless when they are made badly, like any other genre. Just like comic movies all it will take are talented people in Hollywood to treat the adaptions seriously and we won't have so many bad video-game adaptions.
Except many VG movies are from games that don't really have solid stories. They have to realize that a video game experience is based on interactive play. We develop our own experiences. Ryu and Ken are supposed to be the lead characters but any character can be used to win the game. Those two don't even have any relationship with Bison/Vega. You could just throw Chuck Norris or Rambo at another Southeast Asian warlord.
It's the same problem with RPG based games like Dungeons and Dragons. Having the usual archtypes is just the start. A ranger could act like anybody and not be the leader. With LOTR the characters there's already an established personality to each one. That was a planned epic. Sony got the point with Advent Children, but it happens after the FF7 game. Most people don't understand what happened before so it's really fan-based. Great fights but WTF is going on, right? What's with the funky powers?
Horror games are easier. People respond well to horror. You can throw dozens of zombies and victims based on anybody. We'll enjoy the suspense. But the heroes will be harder to define. Some of us prefer heavy artillery for a weapon. Or maybe you just use a pistol. In Doom they don't really need to give us the Martian history. The setting is the character. Just give us an visuals similar to the gameplay. Who the characters are didn't really matter. The super gun was more impressive than the Rock.