I think for a commercial site it can give a slightly more professional feel to your site.
You can also set up a autorespond so that the person gets a "We'll contact you as soon as possible" message. At least they know your site is active then. However, don't incude their message in your auto response otherwise it's a gift to spammers to send messages to whoever they like using your domain.
I don't know what others think but it means that you can also list your email address as an image file (rather than as a link) so that these bots that spider the web for active emails to spam don't find yours. They'll probably find you anyway - especially if your system autoresponds - but there you go - my two penneth!!