"My judgment is that the cultural temptation to triumphalism that has beset the church was powerfully reinforced by the scholastic catechism tradition that took God as 'omnipotent, omniscient, and omnipresent.' Thus, self-sufficient selves in communion with an all-managing God has no room for lament, and that theological premise is now powerfully replicated in so-called praise hymns, in which 'never is heard a discouraging word." (Walter Brueggemann, Disruptive Grace, 180).
I quote this with some trepidation, knowing that I risk being misunderstood. But I'll risk it anyway. The point is that we have a limited ability to practice "lament" according the biblical tradition because we believe in an all-controlling, triumphalistic God. And because he is managing everything from on high, any attempt to cry out to God in lament does no good. In other words, God intended for human trafficking to happen. Or he intended for people in our neighborhoods to be addicted to all sort of stuff. So we are happy Christians who don't see the pain of the world for what it is.
The call to lament is the call to cry out to God because we see the pain, the suffering, and the principalities and powers of the air. We know that the world is not right and that God does not want it that way. And we are in relationship to a God who can and is faithful to do something about it.
And we lament because we believe that our prayers actually have an impact upon this world. Our prayers matter. Missional community is about life together where we cry out to God because we know that it can be different.