The importance of robots.txt Although the robots.txt file is a very important file if you want to have a good ranking on search engines, many Web sites don't offer this file. More information so visit below link http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=40360
True, but why not add one? It only takes a free seconds and I think that worth any advantage it might give you.
Could you please let me know how robots.txt is directly helpful to your website search engine rankings..)