Programming is a much more general skill than plumbing. Don't just think Java enterprise apps for a Fortune 500... programming is fundamentally about learning how to use computers to their fullest. The ability to explore and create with computers is a powerful skill that complements most of the potential careers that a child may pursue in the future. Pretty much any science or engineering field will benefit from programming experience. Increasingly other fields are starting to move in directions that will make those skills more valuable.

Computers are just at the very beginning of revolutionizing the way that human society interacts. Why would you not want your children to have an edge?