In Ephesians 4:1-12 we learn from Paul that Pastor-Teachers (i.e. elders) have been given to the church "to equip the saints for the work of the ministry, for building up the body of Christ" and in verse 15 Paul says this happens by "speaking the truth in love".
In my experience (from my own heart and from what I've heard from other preachers at various times) this instruction is either misunderstood and thus misapplied or it is ignored. Some misunderstand "truth in love" to mean sugar-coating the truth or dodging the truth so as not to offend. Of course being unoffensive is never given as a Biblical definition for love. There is no greater definition of love than that given in John 15:13 which says, "Greater love has no one than this, that someone lay down his life for his friends." Jesus supremely demonstrated Biblical love in laying down his life even for his enemies (Romans 5:8). If you truly want to speak love to another, you speak the gospel of Jesus Christ. To speak the truth in love is to speak truth because of your love. Because I love you, I'm telling you the truth. Now if you love someone you are obviously not going to speak to them caustically, dismissively, or spitefully. Pastors have a responsibility to speak truth to their flock and this should not be hindered by societal expectations of nicety and tolerance.
On the flip-side, "speaking the truth in love" must include the "love" part and this sadly, is often ignored. Over the past five years I've repeatedly been provoked by Peter's words in 1 Peter 5:1-3, "So I exhort the elders among you, as a fellow elder and witness of the sufferings of Christ, as well as a partaker in the glory that is going to be revealed: shepherd the flock of God that is among you, exercising oversight, not under compulsion, but willingly, as God would have you; not for shameful gain, but eagerly; not domineering over those in your charge, but being examples to the flock." I've heard sermons and heard pastors speak of their sermons and to my shame, given sermons that seem to serve the pastor's ego more than the building up of the body of Christ.
There is a kind of preaching that is not given from a love for people to worship God in spirit and in truth but to exhibit the preacher's intellectual prowess, expositional skill, and self-assumed piety. It is possible to preach a sermon that is a careful exegesis and exposition of the Biblical text but not be done in love. Preachers out there, if you've ever preached and boasted later "I really let them have it" or "I hammered them" or spoke of your flock as though they are too stupid to comprehend the deep Biblical truths you grasp and just articulated then you need to repent. I'll be the first to confess I've had to do my fair share of repenting on this. Preaching is not an exercise in demonstrating how theological astute you are and how dependent your flock needs to be on your knowledge.
It is incumbent upon us pastors to recognize the great privilege and responsibility we have to lovingly shepherd those for whom Christ died and to carry out that task with faith and humility. Otherwise we will become what Paul warns of in 1 Corinthians 13:1, "If I speak in the tongues of men and of angels, but have not love, I am a noisy gong or a clanging cymbal."