It's pointless to try and keep cursing out of anything that has to do with the internet. Even with all of their efforts to keep everything nice and family-oriented, Nintendo is unable to make everything perfect.
In Animal Crossing Wild World you can make a hat with a drawing of a Vagina on it, and go into different kids' towns cussing them out (albeit in symbols) all day long if you want to. And you can leave messages on their bulletin boards that say things like "Meowie the Cat is an @$$- Raping $#!t F#*ker."
Trust me Nintendo, people that get on their computers to gather "Friend" Codes also exchanging codes with complete strangers, so you're not protecting kids' innocence or saving the world or anything.