Why do you educate your children? Almost all of the same reasons apply.
We educate our children and train our dogs because we want them to succeed in the world when they are with us and when we cannot be with them. Simply teaching a dog to walk nicely on a leash is not just a cute trick or an obedience behavior, it’s an expression of your dog being calm out in the world and able to function in tandem with the handler. It’s about walking outside together, not being dragged around the neighborhood by a half-feral quadruped.
You train your dog because when people come over, they don’t come over to be jumped on and begged at and barked at and have their shoes stolen and chewed. They came over to hang out with you, not to be accosted by your friendly but presumptuous crotch-sniffing Labrador.
We train our dogs so that we can safely take them out on hikes and onto the beach and let them run and be free and enjoy life. If we’ve trained them, we know that we can say their name and a recall command and that they will happily come running back to us. We can call them back if we see an unfriendly-looking dog approaching. We can call them back if we see an elderly couple or kids and don’t want our dog to scare them or run up to them.
We train our dogs when they are young so that if they do develop any behavioral problems later, we aren’t trying to fix the problem and also teach them obedience at the same time.