Ask HN: Using social media buttons - good, bad, necessary evil?

I run several content education sites, and i've placed facebook like buttons, tweet, and +1 buttons on them for the past few months. While they gather a decent number of likes (a few hundred), the actual facebook referral traffic i get is fairly low (several hundred visits per month). sometimes i think it's just clutter and a waste of space. then i read articles about them (as being necessary for having a social media strategy), see them on other sites, and have doubts. Do you guys feel they're worth it?