I think most of us can agree that games based on movie franchises work out best when the games aren't rushed to coincide with the movie's release. So with that being the case, games made years after the movies will tend to be better than games like Avatar that have to sync up with the movie's appearance in theatres.
The Star Wars based games are usually considered great, and that's because the movies came out 30 years ago so there's no rush to make these games now. Another good example would be the Godfather game, which was excellent on the Wii. The Godfather movie is like what, 35 years old now? The game is great and has a strong connection with the movie, but it wasn't rushed.
So I don't think its fair to say that movie licenses will always create terrible games. The problem is with the rushing. If the developers take their time the movie games can be just as good as anything else. But on the other hand, its also kinda understandable why developers rush them. I mean, how well would an Avatar game do if it came out a year or two later after the hype of the movie had faded away? But if the game was excellent it would probably sell even without the hype of the movie to drive it.
The people who are going to buy movie games like Avatar are the consumers who don't read reviews and most likely consumers that are buying the games for their kids. Their kids might be fans of the movie, so they might think the game would be a good idea. So they buy it and take it home, and a few hours later both parent and child are pissed off at the crappy game, but Ubisoft has their money so from Ubisoft's perspective that's not a bad arrangement. But informed consumers like us who read reviews online or elsewhere are going to know to avoid games like this.