Even Nintendo president Satoru Iwata doesn't think friend codes are prefect. Heck, hear him say it:
First of all, I don't think the current system we have with friend codes is perfect. However, if it's an online world where you can get access to anybody without any restrictions, I as a father do not feel like allowing my daughter be engaged in that kind of world. So for Nintendo, especially in terms of the people who have never experienced online video games before, we think that it's still very important to create a world where we can assure that there will be no harassment for these online beginners, and we really want to assure the security and safety for them to do that. So we will be studying this on an ongoing basis in order to improve Nintendo's own circumstances where people can freely and safely enjoy the communications through the net.
Quick show of hands. Who likes friend codes? Okay, who tolerates them? And, who hates them? Nintendo is doing its best to make sure that its online service is friendly to all players, and the company should be commended for that. (Think of the children!)