There is a real distinction between preaching that tells people what to do and how to do it and preaching that unpacks the text and helps people understand how to apply it in their context. The first tells people what to think while the second helps people evaluate their lives against Scripture and make personal decisions on the basis of the truth that they know.
We have a real need to help people think Christianly. It is easy to share rules and regulations that "evangelicals" would commonly share - which often results in legalism. It takes more skill to help people dig into Scripture and make personal lifestyle decisions based on their understanding of how God's word applies to them along with sensitivity to what the Spirit is prompting within them.
When we tell people what to do and how to do it we make them dependent on us. When we help people understand how to study the Scriptures and make decisions based on what God teaches we make them dependent on the Holy Spirit. While there are many black and white issues in Scripture that don't allow for differences of interpretation there are also many areas that are grey and require real wisdom to discern what our course of action ought to be. That is where helping people think Christianly becomes very important.
Take the workplace for example, where many of us spend the majority of our time. How does God's word apply the amazingly complex issues we face in that environment? If we are to negotiate the complexities of work we don't need a set of rules but we do need some principles that we measure all of our actions against. It is only those who have developed the ability to think in God like categories who will make a difference in their workplace. Telling people what to do will not cut it. Helping them think Christianly in the unique circumstances they find themselves will.
The best preaching helps those who listen think like Christ would think. It shares principles from God's word that go to the heart of what it means to follow Jesus and live out the Gospel. And it helps us evaluate our lives against His Word on an ongoing basis. It is less about telling us what to do than about helping us to think in Christian categories and make the application of the gospel to our everyday lives.