Legalism, Antinomianism, and Christian Freedom all derive from how one sees one's own sin.
Legalism sees ones sin along these lines. Sin X is a sore temptation for me. If I even approach it, say by doing W, I'm going to fall into X. Therefore, W shouldn't be done, and more over, none of y'all should do W either.
Antinomianism sees ones own sin along these lines. Sin X is appealing to me. I mean, really, sin X isn't as bad as that other sin - Sin Y^2. Therefore, come on, really, is sin X really sin, or is that just an outmoded opinion. Let's not even call X sin, that's not really accurate.
Christian Freedom sees one sin along these lines. Sin X is a sore temptation for me. It is forgiven, but when I give into sin X, I harm my neighbor. Even W can lead me to sin X, so for the sake of my neighbor, I will not do W. If my neighbor can handle W... so be it, let him do it. But as for me, out of love for the neighbor, I myself will avoid W.
See, that's the key - I have no problem with adding things that go beyond Scripture as a matter of self-discipline, of fencing the self from sin. Or those under your specific authority (like a father setting limits for a kid). The problem becomes when you either deny a Scriptural Sin being sin, or setting limits on people you don't have to set limits on -- and no, as a Pastor, you do not have the right to set behavioral limits on your members outside the context of the service. You might advise, but you are not their lord.
But really, the bigger problem isn't legalism or antinomianism today. It's this:
Sin? What's that?
God have mercy on us all.