Social media as it is named is a social tool, one created to give people the opportunity to communicate, interact, engage and build relationships. What makes social media real are the people who drive the cogs of communication. Take away the real feel, the people of social media through automation and it won't work as effectively for businesses and marketers.
Automation has a place and can successfully be used in say publishing RSS feeds but the main thing to remember with social media interaction is that behind every computer sits a person with blood pulsing through their veins.
How do you feel when you recieve an automated response via social media?