Why did God kill Uzzah ? - 2 Samuel 6:6-7

> **6** When they came to the threshing floor of Nakon, Uzzah reached out > and took hold of the ark of God, because the oxen stumbled. **7** The > Lord’s anger burned against Uzzah because of his irreverent act; > therefore God struck him down, and he died there beside the ark of God. After reading those verses, I often think this was over-reacted. Maybe Uzzah wasn't thinking badly, maybe was he just taking care of the ark of God ? So what are the deep/fundamental reasons God killed him ? What's your opinion ?