I also agree that they are a design flaw, and that's the reason why I fought so much for that retry button --I had a lot of resistance from some of the directors!
However, WITH the retry button, they become just a funny way down memory lane. --if you are frustrated by them with the option of a retry button, that's just being extremely nitpicky.
Sudden deaths were part of the King's Quest from the past. We wanted to keep them, and we looked at a modern way for you to enjoy them rather than go " oh, crap, when did I last save??" Which was the case with many, many, many Sierra games.
But in doing so, we kept the spirit of it without punishing the player. I think it's a fair compromise to keep the "design flaws" that also made Sierra games, when they are instantly repaired. That's the difference.
I would never add a dead end because that can't be instantly repaired. And that's not just a design flaw, it's an exercise in frustration and it's the reason why I could never enjoy KQ5 and had to play it with a walkthrough --one of the few Sierra games I had to do that with.
That said, I can agree that having added a few mechanic things or just a message from the narrator, would have made it better, but really, again, with a retry button, why are we discussing this one so hard? I find it funny, especially when the Narrator scolds you after that --and no, I don't mind a sarcastic narrator there, you should have known that sticking your hand in a strange hole wouldn't have ended well -it's King's Quest for crying out loud
