Yes because it'll load an image from a domain that expired and is now
controlled by a nefarious third-party. The image is now a payload targeting the
out of date image loading lib used by the onboard entertainment system that has
seen no updates for 5 years.
This entertainment system is connected to the actual driving electronics of the
car that will now brake at full force the next time it reaches 130 km/h.
This scenario is fictional, but possible. cf. the works of Charlie Miller and Chris Valasek.
> This entertainment system is connected to the actual driving electronics
That's the actual problem in your scenario. You can try to blame the kids for having fun all you like -- you might even be able to make it stick -- but it doesn't make you right.
> Well, you shouldn't be doing Y with X. That's the real problem.
What does it matter? If people are doing Y with X, and you as the author of X can improve that path, then you should do that. Normative ideas about what people should be doing don't make a difference.
(You can see this a lot with the Go community. "Go doesn't support [language feature in common use for longer than Keith Richards has been alive]" "Well, you shouldn't be using [language feature in common use for longer than Keith Richards has been alive]" etc etc.)
> X wasn't really designed/is not very suitable to do Y. Why did you resort to do Y with X?
It opens a lot more possibilities and doesn't sound too hostile. Maybe you get to learn that Z which is made to do Y is broken. Maybe a part of that person's workflow requires X specifically. One can learn a lot of things this way.
Consider a person asking about using some surgical equipment on themselves (though they likely wouldn't ask it on StackExchange). Normally, you shouldn't perform surgeries on yourself, but what if you're stranded in Antarctica during the winter night and your life depends on it?
It's worth adding that I agree with the main point that software should be fun, and Easter eggs should be allowed. I'd just prefer to argue for it on the grounds that (a) it's possible to make software fun without making it dangerous, rather than (b) software is fun, dammit, and if that crashes your plane then your plane was built wrong.
That's the actual problem in your scenario. You can try to blame the kids for having fun all you like -- you might even be able to make it stick -- but it doesn't make you right.