You guys know you can add email address's right? So for the people who don't have an email address this can be pretty handy. (I have one, I'm talking about the kids and other people.')
Also, if you think friend codes are stupid please forget off. This is a family console. Kids over three are supposed to be able to play it. With names anyone can just randomly add a name and then the kid could accept it not knowing why he/she shouldn't. Then the older guy who just added a random name sends them researchographic images, thus scaring the child for life. (Well, maybe not that long, but you get the point.)
With friend codes, it is possible to guess a friend code, but the chances of them guessing right are much lower than with a name.