Why was David disqualified from building the temple?

From 1 Chronicles 22: David said to Solomon: “My son, I had it in my heart to build a house for the Name of the Lord my God. But this word of the Lord came to me: ‘You have shed much blood and have fought many wars. You are not to build a house for my Name, because you have shed much blood on the earth in my sight. But you will have a son who will be a man of peace and rest, and I will give him rest from all his enemies on every side. His name will be Solomon, and I will grant Israel peace and quiet during his reign. He is the one who will build a house for my Name.

Seems obvious to me David was not allowed exactly BECAUSE he had fought many wars and shed much blood, though God's priority and command to the Israelites was that they exterminate the Canaanites. Could it be because David took warring too far? Could it be that he had shed too much 'innocent' blood? Or might it be because, for 'good' or 'bad', being a man of war was God's role and will for David, it was now David's reputation; perhaps God simply determined a different role/tone for Solomon and his kingdom?

When David provoked the anger of God by counting the fighting men in Israel, the punishment was so severe. Then God commanded David to build an altar on the threshing floor of Araunah the Jebusite (1 Chronicles 21) to pray to the LORD to have mercy on Israel. David called on the Lord, and the Lord answered him with fire from heaven on the altar of burnt offering. David then decided to build the Temple there at the threshing floor of Araunah the Jebusite. David then commenced the building of the Temple of God immediately. But God already forbade David from building the Temple as David had shed much blood.

1 Chronicles 22:1-10 (NIV)

Then David said, “The house of the Lord God is to be here, and also the altar of burnt offering for Israel.”

So David gave orders to assemble the foreigners residing in Israel, and from among them he appointed stonecutters to prepare dressed stone for building the house of God. He provided a large amount of iron to make nails for the doors of the gateways and for the fittings, and more bronze than could be weighed. He also provided more cedar logs than could be counted, for the Sidonians and Tyrians had brought large numbers of them to David.

David said, “My son Solomon is young and inexperienced, and the house to be built for the Lord should be of great magnificence and fame and splendor in the sight of all the nations. Therefore I will make preparations for it.” So David made extensive preparations before his death.

Then he called for his son Solomon and charged him to build a house for the Lord, the God of Israel. David said to Solomon: “My son, I had it in my heart to build a house for the Name of the Lord my God. But this word of the Lord came to me: ‘You have shed much blood and have fought many wars. You are not to build a house for my Name, because you have shed much blood on the earth in my sight. But you will have a son who will be a man of peace and rest, and I will give him rest from all his enemies on every side. His name will be Solomon, and I will grant Israel peace and quiet during his reign. He is the one who will build a house for my Name. He will be my son, and I will be his father. And I will establish the throne of his kingdom over Israel forever.’

Prophet Nathan also prophesied long before David married Bathsheba, the mother of Solomon, that David was not the one to build the Temple.

He is the one who will build a house for my Name, and I will establish the throne of his kingdom forever. I will be his father, and he will be my son. When he does wrong, I will punish him with a rod wielded by men, with floggings inflicted by human hands. (2 Samuel 7:13-14, NIV)

Before Solomon was born, God already decided that Solomon should build the house of the Lord. David was not qualified because his hands were stained with blood. Moreover, David's purpose was to establish the kingdom of Israel. After 300 years of war with the inhabitants of Canaan, it was time to make an end to turmoil. David had the responsibility to build a powerful nation for Israel, the people of God. The reign of Solomon was the right time to build the Temple. God wanted to build His house in a peaceful environment, without shedding of blood in the country. After David defeated all enemies of Israel, the nation was in peace and his son Solomon received the honor of building the Temple of the LORD.