SpoilerI'm thinking it's their family and neighbours and they kept them in the barn because the house owner guy doesn't seem to like violence rather than because they think they can save them.
I suspect the lack of action might be down to budget constraints compared with the first series. Hopefully they're saving up for some big budget action later on.
I'm inclined to agree with Abradix in thinking tat the zombies in the barn are family members who Hershel wishes to save once a cure gets discovered. Otis didn't seem to have a problem killing zombies when he was out with Shane, so I don't see why Hershel would either.