You teach them to read. You teach them to look both ways before crossing the street.... and to be kind to others, and to brush their teeth before bed. But have you taught your kids how to do the dishes?
Cleaning up after oneself is an important life skill - something that every child should learn, not just to endear themselves to future roommates or spouses, but to feel like a contributing member of the family unit. Children may grumble at first, but ultimately, they want to be useful.