I don't understand why people hate friend codes so much.
They are like phone numbers, you enter them into your phone once, then it doesn't matter anymore. Plus having your account tied to some number, means than multiple people can have the same name, so you don't need to have people like xX-Goku9720-Xx just to have a unique name. It also means if you want to change your name it should be free, since its only really your number that means anything.
It's not a big deal, and there is some really good positives.