Reading about judo on the internet I found an article at judoinfo.com (link below) that I think talks very well about why Judo for kids is great. While I’ll summarize some main points but you should follow the link and read the whole article.
Self-Defense – being able to defend yourself.
Self-Confidence – improving and the mentoring of their Sensei will improve their confidence. Belts and Ranking helps them see their effort rewarded.
Exercise – both physical and mental. Physical will build strength and coordination. Mental will come from learning moves and learning the Japanese terms for judo. See or FAQ for some examples to practice.
Family bonding – the whole family can learn judo, giving an opportunity to share in the learning.
I can add one item, while judo is not a team sport it does teach respect for other practitioners and teamwork lessons in the roles of Uke (one being thrown) and Tori (one practicing the technique). A tori must always beware of how they performa a technique to protect the wellbeing of their uke. The uke and a tori are a team working to get better. Both can learn from a throw, and help each other improve.
If this interested you please head over to http://judoinfo.com/judo4kids/ and read the full article.