Assumptions leave out the Gospel

This is just a pet peave of mine, but I think that it has a lot of implications on the church and our music. Zach and I were talking two nights ago and we were discussing why the gospel is left out by so many preachers (and music writers). Our conclusion came to two assumptions. One, we think that many times, pastors and others in authority assume that everyone knows the gospel and its implications, then jump to what we as Christians need to do. The second is that they assume that the Gospel is only needed for salvation, and not for sanctification. If we loose the Gospel as sanctifying, then we loose the power that leads us to do the things commanded of us in the Bible.