Although the robots.txt file is not needed, it is a good idea to use it. My site's robots.txt file is: # Robots.txt file created by 7/21/06
# For domain: [catanich.com...]
# All other robots will spider the domain
User-agent: *
Disallow: */_vti_cnf/ #created directories by the dev tool
Disallow: /_common/ #common source code
Disallow: /_holdit/ #a junk folder
Disallow: /_private/ #
Disallow: /_ScriptLibrary/ #common script folder
Disallow: /rLinks/ #reciprocal link folder
But when I ftp my site upto the server, the "_vti_cnf/" directories are sent too. This means that the SE's will index these directories as well (thank you Python Site Map) and create a great deal of Google errors.
In addition, I don't want my source code directories to be indexed.
And just for information purposes, by adding "Disallow: /rLinks/" to the robots.txt, all my reciprocal links are blocked from being indexing. So no PR bleed.
So as you can see, there are real reasons that you use the robots.txt file.
Jim Catanich