There are just one reason why it is made video games out of game and there is an expression covering it to perfection. Milking the cow. They want to squeeze as much money out of one concept as possible. They desperately want to get the last piece of money out of the movie by pumping out all sorts of merchandise including a half finished game on every console known to mankind. The reason they do it is that they know that it works. People do actually buy those games for some unknown reason.
The fact is these kind of games don’t do us no harm. It is not like we are forced to buy them and they don’t stand in the way of game designers making good games since they are mostly so fast made and made by companies that have no good games it doesn’t matter. The games can be entertaining for children, but most of them are short and repetitive. The obvious major factor that drives developers and game makers to make this is the profit. When people buy it then there is money in it and then it is worth it for them. Every game designer makes game for profits and if they can get easy money out of people that enjoyed some movie then they will try.
There are of course annoyances for us gamers when 90% of the games that are released don’t appeal to us at all. You have some crap games, some children games and then the wide specter of movie games. Some of them are actually good of course, but those are the one mostly based on old movies. Like Star Wars games and Lord of the Rings games can actually turn out good. However then you have the games made together fast so they are released within the momentum of the movie. Games like every single Disney game and games to such things as Lost (the TV series) and all one hit wonder movies. Like the Eragon game is a good example of thrown together. This does not hurt the game industry, but it certainly doesn’t help it either that some companies spend time on that kind of crap instead of releasing quality titles. If people would just stop buying half assed titles put together from random cut scenes from a movie and bad gameplay we would have no problems with it. But until that day the unwanted games will remain as they are no so unwanted as they should be. As long as those games stay away from me I’m not going to complain too much.