Being a computer animation major, you must have no idea how much work is being put into CGI, especially considering this film that involves CGI robots interacting, having action scenes within the whole movie.
Just imagine one person animating a small character doing a 5 minute role. That can take tons of hours broken up into days just to do. Whether it is motion capture or key animating, it is a tedious task that folks with patience can basically endure.
Now put that within a big budget film with advanced hardware and all that junk. Everything needs to be perfect and fluid in terms of motion. That's just tons of work. It makes so much sense to take that long on a film of this caliber.