Here's a quick question: how many good video games based on a movie are there? And if these games are mediocre at best, why do we keep buying them? Actually, scratch that. I've stopped putting my trust in movie games ever since I finished playing the games based on the Lord Of the Rings franchise. In recent memory, those games probably are the exception to the rule; good production value, excellent feedback and collaboration with the original cast members, and really epic fights.
Of course, this is not the case for other recent games. Can anybody, in any good and rational conscience, say they had a blast playing Alien vs Predator, The Golden Compass, Garfield (???), or even Spider-Man 3's game? If there are, please, do us a favor, and punch yourself in the nuts.
How many sucky movie games are actually better than their suckier origins? None that I could think of.
This is a problem. Movie houses think that just because a movie is a cash cow, they can produce a game that everybody will lap up, irrespective of their quality. Never mind whether it was a shit movie, or the best movie ever, more often than not, the game adaptation will probably suck humongous donkey balls. Mediocrity is the product du jour of lazy publishers, writers and programmers.
Voices by the actors themselves? Wow! Robert Downey Jr. and Gwyneth Paltrow doing the voices in the Iron Man game? That must make it really, really awesome. Unfortunately it didn't; the game was boring as hell, repetitive and generally an insult to anyone's intelligence.