A good reason for turning down tattoed applicants is that certain societies find them offensive. eg the Chinese consider a tatoo as a sign of being a gang member.
Self-expression is all very well for the individual, just don't expect everyone else to accept you, just becasue that's the way you want to be and 'it's your right to freely express yourself.'
Personally speaking I don't like them and yes, I would prejudice against a tattoed individual for the reason stated above.