Stephen Holmes, in his book God of Grace and God of Glory, says this about why proposing a logical order to God’s decrees is important:
Decrees are, of course, not before or after one another in time–they are all alike God’s decision from all eternity–but they may be logically, and this in two ways. Firstly, decrees that are means to ends can be regarded as consequent on the decree of the end that is in view; secondly, if one decree presupposes another, it may be regarded as dependent on the decree of the thing presupposed. So, God’s decree to punish sinful creatures is consequent on both the decree to glorify Himself–the end to which this decree is a means–and the decree that (some) creatures will be sinful–the necessary basis for this decree.
Stephen R. Holmes, God of Grace and God of Glory: An Account of the Theology of Jonathan Edwards (Edinburgh: T&T Clark, 2000), 128.