Alot of stuff was taken out of the game at the last minute. If you look at the vids Peter explains u can make walls as big as you want, and early screenshots would have prooved it the game of the year.
Nobody knows why..
Some of the removed content promised could be explained away as it making the game unbalanced. Most of the stuff we've seen in screen shots probably fall under this category. Others that were promised but never seen are probably down to the fact of they would either eat up too many system resources for the extra feature they'd supply and those resources could be better used elsewhere. That or it would've taken too long to develop with little reward for all the work involved.