[trackercowe]

Probably because Hollywood is incapable of developing new ideas, and even when they do they often fail to bring in an audience (see Cloud Atlas). That and the money thing of course.

The Wachowski's careers haven't exactly taken off since the Matrix, and they probably think they need to go back to the well to turn their careers around. Who knows if that will even work considering the last two Matrix weren't exactly smash hits at the box office.