Chasing photorealism in games seems misguided to me; you have to spend much more money on artists. And at the end of the day, photorealism won't make a bad game into a good game; so that money is better spent on other aspects of the game. Furthermore, if you're committed to spending that much money making a game, it will probably have a very conservative lowest-common-denominator design to recoup as much money as possible. Who will take risks and experiment when so much money is on the line? You end up with a game that is mediocre to everybody but exceptional to few. The video game equivalent of a big budget marvel movie.