This sounds strange, but I find that it is sadly all too true in much preaching. Too many preachers find it easier to criticize those persons who are not part of their church during their sermons, than those individuals who are actually sitting in front of them (in a general sense, of course). I know of one retired Methodist pastor, who on regular occasions, aimed his barbs at conservative fundamentalists, even though there were none in his church (if there were a few, he drove them out a long time before). In that same town, a Baptist pastor regularly railed against all the Methodist liberals. Of course, there wasn't a liberal to be found in the pews of his church.
Prophetic preaching isn't very prophetic when the preacher does not have to suffer the consequences of words that may stir things up. I am not suggesting that pastors intentionally create problems by addressing difficult issues, but the gospel of Jesus Christ has a hard edge to it, whether one considers himself or herself conservative, liberal, or somewhere in between. The Old Testament prophets did not rail against people who lived thousands of miles away. They directed the Word of the Lord to their own audience. It takes courage to do such a thing, and prophets need courage; and frankly, it is quite cowardly to critique those who are not there to respond.
My suggestion is that we mainliners let non-mainline preachers critique their fellow non-mainliners, and let's look to the log in our own mainline "eyes." There are plenty of strange and weird things happening in our own UMC to keep us Methodist preachers in sermons for the rest of our careers.
Moreover, I would request that those pastors outside our tradition, allow us to deal with our own house as you deal with yours. Fundy churches have issues too, and we will trust you to deal with them; trust us to handle our situation as well.
I am not suggesting that there should never be a wider discussion and/or debate in the larger context of the church universal. We are all Christians, and all of us have a stake in the witness of the one, holy, catholic, and apostolic Church, but there are other venues for that. When it comes to prophetic preaching from the pulpit, those sitting in front of us are the ones listening to the sermon. My task on Sunday morning is to preach the gospel and to shine its light on those in front of me, as well as on my own life, not on those Christians down the street who are listening to someone else.
The task of preaching is more than prophetic, but it is necessarily prophetic as well. Historically, prophetic preaching got the preachers in trouble. If prophetic preaching has made you popular with your church, you are preaching to the wrong crowd.