I think for ourselves families are a real potential source of business. If you're a bit off the tourist route it can be hard to attract the young backpacker crowd. If somehow one of the party crowd end up here they are often shocked by the lack of pub/nightclub/fast food/anything to do. But we are rurally located and getting away from it all is supposed to be a draw.
I think if it's done right then families can really benefit from a hostel's facilities. If you stay at a hotel with kids you often end up stuck in your room - there may be only a bar there which might not make kids welcome. Kids love coming to a place with a common room/ dining area etc that they can run around in - and still be able to kick a football around outside while the parents can supervise.
I guess the problem can be one of the short season - usually co-incides with school holidays only. Most families we get in seem to enjoy themselves though - had one extended family in an 8 bedded dorm last night, they had a ball. Though I didn't vacuuming the carpet this morning!