Playing a musical instrument seems complex as an adult if you never picked up any such item and touched something to make a sound, and the complexity gets even more scary when you look at written notes 'cos it just looks like the language of an extra terrestrial, however a child will naturally play and make uniformed sounds because it is new and of interest. It's the same way they learn to speak the native language.
Being a master of an instrument will teach so many life aspects: curiosity, balance, logic, self-control, discipline, desire for perfection and achievement.