MacDonald and others pick up on the desire of congregations to be entertained and made to feel good about themselves. Believe it or not where I am the complaint is that they are hearing too much about grace and they want to hear more about judgment. But ultimately that too, is just about wanting the sermon to make you feel good. It's just that some people feel good hearing about how others are going to be judged. (because this wish to hear about "judgment" is a wish to hear about how OTHERS are going to be judged)
I think a large part of clergy burn out is the lack of recognition of pastoral authority. I am alternately perplexed, offended and disheartened to find how people think they can and should tell me how and what to preach. What wears me out and saps my energy and makes me want to go home and play Farmville on Facebook is the reality that people don't trust or believe what I say about the Bible or church teaching. They have their own opinions, thank you very much. And if I challenge those opinions, they can always find someone else on the internet who agrees with them.
I went to an ordination yesterday. It was wonderful. We old clergy need to go to more ordinations. The newly ordained is presented to the congregation with these words
"He/she has Christ's authority to preach the word of God and administer the sacraments, serving God's people as together we bear God's creative and redeeming love to all the world"
Authority. CHRIST's authority. Yes Lutherans are all about the priesthood of all believers but we also believe and teach that God has established the office of ordained ministry to ensure that the gospel is proclaimed and the sacraments are administered.
Now I know that a lot of pastors have abused that trust and that has contributed to this lack of trust in authority. But sin among the laity is also part of the problem. We all want to be our own authorities. Well sorry I know more about the bible than you and I have more right than you to be listened to about the bible. Not because I'm so smart (which I am) or so well read and educated (which I am) or so morally superior (which I am not) but because of the OFFICE of the public ministry of Word and Sacrament.
That's why we educate pastors --that's why we pay them enough (or should) so that they can live among us and do nothing but continue to study the Word and proclaim the gospel and see to it that people are baptized and fed at the Table. People want us to do a whole lot of other stuff and that other stuff can wear you out but you know I could do all that other stuff you want gladly if you would just TRUST that I am telling you the truth about God.