I have always felt bad for Uzzah for God striking him dead for touching the Ark. Wasnt Uzzahs reaction basically involuntary when he reached to steady the Ark when it became unstable? He couldnt have had any conscious intent to purposely disobey God’s commands regarding the handling of the Ark.
When dealing with the holiest of issues, one must take responsibility and make sure from the very outset, that such accidents don't occur. The Torah explicitly teaches in several places, that the Ark should not (!) be taken by wagon as many of the other utensils of the Mishkan, but rather must be carried by hand by several Levi'im/Kohanim (Bamidbar 7, 6-9; Dvarim 10, 8; Joshua 3, 13), which would prevent such accidents. This is also clear from the account in Chronicles, which clearly writes that King David learned his lesson and afterwards had the Ark carried by hand by the Levi'im and not by wagon, "as commanded by Moshe by the word of God (I, 15, 11-15). This teaches us the important lesson in life, that regarding serious issues, there are ramifications for not following the rules.