What documented flaws are you talking about? You make it sound like people who don't patch a security issue they don't know about in their router are idiots, which is probably not what you meant. 
It was an analogy about SnapChat, not actually meant to discuss the security of modern routers, dude.
whereas the obviousness of a gadget or app which you're allowed, asked and encouraged to use being dangerous due to risks it doesn't mention on the tin is on a completely different level.
It doesn't take willful stupidity to be unaware of risks of the digital world, whereas it does take willful stupidity to think you can fly an airplane just like that (unless you're mentally retarded enough, or lived your whole life in a jungle or a test chamber without any exposure to the possible risks).
Really? It doesn't take willful stupidity not to notice that the images you transmit can be preserved with nothing more sophisticated than a camera and that this completely breaks the so-called security feature of the application?
P.S. It seemed like a third-party website claiming to be a front-end to Snapchat was to blame, not anything on the receiving end.
It's a third-party tool that allowed users to log into SnapChat through it and thereby save incoming images. In short - it's a highly automated extra camera snapping pictures of your screen, a security flaw that was completely predictable, especially because SnapChat's only means of deterring third-party app use was via the terms of service. That tool then appears to have transmitted people's images to a server.
The flaw remains the same - you are using a tool (SnapChat) that relies wholly on the goodwill of people you are transmitting the images to to ensure they are never released. There's no actual security model, which is patently obvious, and anyone who had personal information compromised as a result is quite frankly the author of their own misfortune. If you send personal information over the Internet in a medium that is insecure on its face without control over how it's used, then it shouldn't be shocking when it is misused.
The celebrities were victims of an actual criminal act.
This is different.
I'm not convinced this is the case. Leaving aside the victim-blaming "people should know better" position, this is still clearly a criminal violation. If someone walks into your house in the middle of the day because you left it unlocked, it's not breaking and entering but it's still sure as hell trespassing.
Funny story - this actually isn't a criminal violation. At least, not by the person who received and ultimately compromised the photos. It's the same reason most revenge porn is not illegal - images consensually sent are not protected by criminal law from distribution in a manner not intended by the sender. Basically, when you transmit information you give up control over it. While the third-party app's storage of the photos it captured for the recipient could potentially be a criminal wiretap/intercept, that wholly depends on the way it's usage rights were set out when people used it to sign in to SnapChat. That's what makes this so different from the CelebGate mess - this wasn't actually a hack. Quite probably there wasn't anything criminal about it. It's just someone exploiting the idiocy of potentially a lot of other someones.
Which is why I'll repeat myself: if you transmit your information over a service that has a broken security model on its face, you'd better be damned sure you're OK with the public release of that information.