While I _mostly_ agree with this, a nice policy management (configuration management mostly) tool is also essential when dealing with lots of boxes. You want a new setting for all Gnome desktops, simply add it to the policy tool and let it distributed any required config files or run commands to change the setting, etc. This type of thing used to be done with things like: for h in $all_my_hosts; do ssh $h /tweak/some/setting; done
CFEngine and Puppet and friends are a nicer way of doing this. They're "self documenting" in that your write the code and then you can later very easily see when you added some configuration bits, etc...version control your configuration management scripts and you get even better tracking of who did what and when. (A side question: How does one do the version control type stuff in AD?)
While kickstart is great (I use it), it only goes so far. Having a policy manager on top of that (installed and configured in the kickstart) is a beautiful thing!
-Ben