I guess the issue is that players like myself struggle to see the value in making mechanically explicit the sort of social interactions already encouraged by the backgrounds and their associated personality traits, flaws, etc that are featured in the PHB. Should there actually be a huge demand for social combat systems and the like, I think WotC should publish a book on them, but if there isn't actually a huge desire for them, 3PP should cover you just fine, especially given the fact that we live in the information age and something written by a random individual online could be just as good as something published by Kobold press.