Because it's not worth re-implementing the functionality available in Jenkins, Chef, etc. etc. etc.
Automation should be tooled to the production environment by people who are familiar with the production requirements and -- most importantly -- by the people who will be expected to maintain the environment and respond to critical issues.
I'm curious about this -- what's wrong with using the same deployment tool for running dev _and_ the other environments? Jenkins itself is a life-saver for, like you said, doing development builds/testing/reporting, but if we've got one script that deploys an image to production, why not trigger it with a Jenkins job, if only to keep everything centralized and maintain coherent deployment histories?