Well, I disagree with forcing hospitals to treat people in an ER, but that's beside the point.
Yes, the cost is passed on because some people are assholes and don't pay their bills. And most of the folks I've encountered in the ER DID have insurance, they had govt insurance. (which usually meant they got even crappier treatment) But if we remove the mechanisms that raised the costs and keep raising them, we can lower the costs and fewer people will skip out on their bills. Well, that may not be because lower costs aren't going to turn assholes into moral people, but at least the bills that are skipped out on will be lower.