What Nintendo sadly doesn't realize is that being "Family-Friendly" is impossible in 2013.
You could buy your kids Dr. Seuss books up the wazoo, set child block so that it only shows PBS kids/Disney JR, never let your child go on the internet at all, shield them from the newspaper, the works. You can't stop some kid at school from showing them naughty stuff on their smartphones, or forbid them from listening to their playgroup teacher's relationship phone calls. Does that mean you have to invoke helicopter parenting, or home schooling? By all means no. Unless you want to hide our big beautiful world and the good people that inhabit it from your child.
What society accepts as family friendly stuff during whatever year will always be different from what was accepted before. Simpsons now has massive amounts of products for the young'uns', where as during it's infancy, it was considered inappropriate for minors. Batman's massively popular, but before that it spawned a massive thesis on how it was horrible for developing minds. (It was called "Seduction of the innocent", I believe.) Literary classics regarded as all-ages now, such as Tom Sawyer, were despised by protective types back during their first publication dates.
So Nintendo, here's the thing. Like the parent listed above, you try to protect the innocent. You can act like certain series that don't fit this quota (F-Zero, Mother, Metroid, Text-adventures) don't exist. You don't let them voice chat with strangers. You don't tell them everything when they ask you things, as you have skeletons within your closet (Hiding the transgendered Mario characters, Refusing to say the G-word even when whole games plots (Diamond/Pearl) revolve around it). But you can't stop children from going on avenues you don't own and being naïve with their information. You can put up barriers, such as the moderation on Miiverse, but you can't fully control the path of those you're trying to protect. No parent fully can either. Does that mean you shouldn't allow anything ever? No way. Instead, if you really want to continue on the daunting task of being family friendly, you have to admit that not only are there scumbags out there, but there's also good people out there as well. More so then the scumbags. These good people look out for their friends and family, with or without your interference. Until that idea has been realized, you'll never be able to truly make things that are family friendly; as the family of 2013 consists of more than just the child and their parents.
tl;dr: Times change and you can't protect everyone every time, but Nintendo should've anticipated system abuse/scumbags before creating a "Friend" messaging service and have instigated moderation on photos; if they want to still be family-friendly. Or as some have said, an account system, so that the bad apples can be removed without leveling the whole orchard.
Hopefully this makes sense. I was struggling to conclude my thought due to how late it is where I am, so if it sounds disjointed near the end, I apologize in advance.
