Is your audience active in the social sites?
Are you active in the social sites?
If you answered yes to both of those questions, then it is probably worth it to link to the social sites. Otherwise you might want to reconsider. There is a chance of potentially diluting the link juice by adding unnecessary links and let us not forget the potential risk to usability by crowding your page layout.
I have redeveloped many websites and when it made sense removed their social links and other times I have added social links. I have been able to achieve positive change both ways. It depends on your situation.