It's done purely so we are all working/flying off the same page. Structured right or wrong we have to have 'standards' as aviation grew from hapless barn storming pilots who pretty much dd their own thing in order to land with more than a couple in a particular ares for a Ldg. When all over fields where the go circuits as we know it now wouldn't make sense so now that we have 'direction' we have order
Well supposed to but I all too often I see pilots who haven't got a clue about basic airmanship, something obviously not taught more often than not!
Wmk2