>It's an old fallacy. The costs of maintaining, modifying, enhancing, and testing your own code as well as the time lost that could be used on other aspects of the system (opportunity cost) typically exceed the costs of doing all that you've said.
Assumptions
>A good, automated system to generate installs sets & scripts and actually do the installation goes along way.
We have that
>If you have thousands of pages of documentation, something is wrong.
Go tell that to the higher hierarchy :)