When it's used, someone has already done all of that. The unboxing is the special part.
Even if the item is used and the box it came in is not the original from the manufacturer, I would still tend to leave it in whatever box it's in to allow the person I'm giving it to to open.
Once it's been done, it behooves you to examine the unit to make sure that there's nothing wrong with it, because gamestop sure as shit doesn't care. They don't test most of what they buy adequately before sending it out.
You know that, and I know that. These parents didn't know that. Any other reputable business would have made sure the item they were selling was in an appropriate condition before selling it.
Who hasn't got a bad used controller from them, for example?
Me. I've never gotten a bad used controller from GameStop. Why? Because I don't shop there. I've never bought a used controller there, so I haven't had this personal experience. I'd bet these parents haven't either.
Why would you expect that? Firmware updates anyone? You should expect it to behave however it behaves when you turn it on, because it's used and it can be tampered with.
Some electronic devices have an initial setup process. I would expect that when buying a used one from a store, it has been reset to factory defaults so that if there is a setup process, I'll be prompted to go through it the first time I turn it on. Since I don't have a 3DS, I have no idea if it has something like this or not.
If I bought one from an individual, I would not necessarily expect that they had returned it to factory default settings before selling it to me. I would expect that when buying from a store.
If they don't understand the issues involved in buying a used console, they should buy a new one.
And what exactly are "the issues involved in buying a used console"? What would you suggest responsible parents should do to educate themselves about these issues before making a purchasing decision?
Or perhaps they should learn something about the things they are giving their kids before they give it to them and even if they find it uninteresting, like a handheld video game. That's called responsible parenting, and while I understand it is largely a recurring fad, it's still a good idea(tm).
They probably did learn something about the 3DS before purchasing it, but what they learned didn't include anything about it being pre-loaded with porn.