Just discovered a helpful article on Wikipedia summarizing the redemptive-historical approach to preaching:
The proponents of this kind of preaching argued that Old Testament narratives are not given – primarily – to us by God to be moral examples, but as revelations of the coming Messiah…Opponents of redemptive historical preaching often fault this type of preaching as being weak when it comes to practical application of the Bible. Because the moral examples given in Scripture are undermined or diminished, redemptive historical preaching often fails to challenge the listener to conduct consistent with Scriptural direction given in places such as Matthew 5-7, Romans, and the Pauline Epistles.
I look forward to exploring this issue more. Not sure I've resolved this one in my mind quite yet.