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.