Endpoint security is about protecting the access points, or entry points, into your network. These points are definitely where viruses and hackers can do the most damage infiltrating your network, because typically they're the least guarded areas of a network. I recently wrote a guide on Microsoft's endpoint security feature, called network access quarantine control, which you can find on this site.
Should you care about endpoint security? I think so. It's like exercising each day for internal cardiovascular health but inhaling sneezes all the time – you're protected adequately internally from chronic diseases but your external orifices are still a prime vector for infection. So it may be a buzzword, but it's one worth following.