Equality. The uniform represents a democratic ideal of equality. Boys from various cultures and different economic levels wear the same uniform and cooperate as equals.
Identification. The uniform identifies a boy as a member of the Cub Scouts. Badges on the uniform tell other members that he belongs to their den, pack, and council. The uniform itself identifies a good citizen to the entire community.
Achievement. The uniform displays badges and other awards so the accomplishments of each Cub Scout can be immediately recognized.
Commitment. Wearing a uniform is a constant reminder to each Cub Scout of his commitment to the ideals and purposes of Cub Scouting: duty to God, loyalty to country, and helpfulness to others.
One they didn't mention is that it just looks awesome! I can't begin to explain how proud I felt the first time I saw my boy in his uniform. Although I don't think I was half as proud as he was!
I think the big thing that each of these points to is that he's a part of something bigger than himself. Hopefully, each time he puts on that uniform, he's reminded that he should be holding himself to a higher standard, that more is expected of him. That's just one step toward becoming a leader.