"Lessons from the past" are important, but not always easy to transmit. 

This Psalm is dominated by an overview of Israelite history, with a remarkable focus on where they failed to stay faithful to God. It seems the main point is that "God cared for them" even though "the people kept sinning". It is interesting to reflect on how well lessons from the past are handed between generations in our own society, and indeed which lessons are most important to pass on.