I think one of the reasons is time considerations. I remember they had to edit out about 30 minutes of "Attack of the Clones". I think IMAX for some reason is limited to around 90-110 minutes which would explain one reason why Hollywood hasn't embraced it yet.

Edit: I found out most IMAX systems only go for 120 minutes, so I was a bit off.

[This message has been edited by Jed M (edited June 01, 2004).]