I had an email enquiry from my website asking this question (I have slightly edited it for readability): 

John Piper said, "Nothing ever comes into God's mind. He never learns anything

 If God is omniscient, he knows all things all the time.  Also Wayne Grudem's, Systematic Theology, p. 190 says that, "God fully knows himself and all things actual and possible in one simple and eternal act."

If this is true, that nothing enters God's mind, would debating the order of decrees be a moot point, since there is no logical or even temporal order?

.  Lastly, maybe the hardest part in answering and understanding the answers to questions like this is how well you can grasp what it means for God to be “infinite.”  Most are not willing to tune out of their vain lives from this world and its entertainments long enough to submerge themselves into the deep treasures of God’s radiant Glory.

Therefore: Ecclesiastes 7:8, "The end of a thing is better than its beginning."

God knows all things in a continual eternal act, yet He orders these thoughts of His pleasures, which turn into His decrees, which finally turn into His will for this time and day as we see it unfold before our eyes.  God's willing or will is His present action.  For no power is power other than His will itself, which actively brings things into present existence. 

The key bridging the truth that God knows all things and never learns anything and yet He decrees the future is His pleasure.  Take for example that God does not need to create anything.  Yet it is proper, right, good and in some measure necessary that infinite beauty be displayed, that an infinite fountain should properly spring up and abundantly flow out in a brilliant display.  God does not need to display His beauty, nor does the Father need to publicly honor His Son, Jesus Christ, by making His the first born of creation giving His the Supremacy, yet it Pleased the Father to do so.

Therefore, in all God's thoughts of going public with His infinite beauty and worth, to honor His Son, to do this with a public audience, His Pleasure took this and organized them into a concrete order of decrees, which one day becomes reality by the power of His will.

Yet, the risk here is that by saying what I said, it might appear that God was existing for a long time before He ordered these thoughts, and therefore, He learned something new.  We must understand that from a human perspective it might seem this way, but God has already warned us not to use stupid inductive reasoning to know who He is and what He can and cannot do. (Psalm 50:21)  Because God is truly an infinite Being, (and I say infinite as strongly as I can!), His mind is infinite and therefore, there is really no time perceptive or time deterrence between God's thoughts and His pleasure decreeing a exact order of them. The Divine mind, if you would, is so infinite that He can do all these things in His mind in the same eternal act.

Ephesians 1:10, "He purposed in Himself, that in the dispensation of the fullness of the times He might gather together in one all things in Christ, both which are in heaven and which are on earth -- in Him." 

God knowing a thing's end is better than its beginning, decreed that man will fall so that Christ would come and therefore, the ending of man is better than his beginning, which also makes God's glory shine brighter at man's end than at his beginning.  This was done by God's decrees, showing His Wisdom!

Therefore, it is not a moot point because God's goal is to showcase His Glory, and in particularly His wisdom of ordering!  For what does Paul say after stating the decrees of God, before time, ordered that Israel should be blinded until the full measures of gentiles come in?

Romans 11:33, "Oh, the depth of the riches both of the wisdom and knowledge of God!"

Therefore, if the displaying of God's glorious wisdom is not a moot point, then the order of the decrees are not a moot point, because the scriptures often directly tie the decrees of God to His greatest displays of wisdom. [1]

Sincerely: Oshea Davis

http://www.osheadavis.com/

[1] This is the main, or most direct scriptural reason why the decrees of God are not a moot point, so that even if you did not understand what I said earlier, this is plain enough for any believer to understand, bow, and love their Great God more for this particular truth.