So, here's the thing, people are constantly surprised at just how far a little bit of social will go. I've complained and whined about it on here before, but most games just aren't designed to rake you over the coals as hard socially as they are with combat. But even more than that, unless your character is looking to dominate in the social arena it isn't an area you need to focus a ton of points on.
That doesn't mean you can ignore it. It just means that it can be a good place for a side venture rather than as like a secondary primary.
Speaking To Kings Is Dangerous
This is kind of the stick to the above's carrot. The danger in having no social is that as you improve in status and skill more and more powerful people are going to want to interact with you. Now, mysteriously, the people holding onto power are often social. Why? Well, throughout history whomever controls the purse controls the power and even if a sword can kill you now an army marches on its belly. So no matter how good your army is, if you can't feed them they're useless and that takes money, and keeping/earning money takes social ability.
On a more individual level though people in power can be easy to offend and as good as you are, odds are that King you just pissed off has dozens of guys capable of bumping you off. In games like L5R and Vampire it might even be more direct than that. The point is simple: you want to be able to make a few basic social rolls when the time comes. It just makes everything a lot easier.
Games Aren't All Rolling Dice
The biggest reason for this though is it gives you more to do. No matter how combat focused a game is there will be times out of combat. Having a character who can do stuff out of combat frees you up to do more.
For example, in the L5R game I'm in my straight up combat bushi is going to branch out into tactics and some social stuff to represent her clan in the area she is. The tactics means she'll be able to participate in the war tent between fights to contribute to the story line (currently involving a Crane clan civil war) and the other social skills will let her not be completely ridiculed, shamed, and laughed out of where she can be functional. It will also let her participate in more social/courtly scenes even if she's not the focus.
In the end, the more your character can be involved the better, no?