I understand the reason to delete unclear or too broad questions. In short, it bases on the broken window theory, which states that minor forms of bad behavior encourage worse ones. A neighborhood with lots of graffiti and broken windows becomes one where robberies occur.
However, unlike off-topic or exact duplicate questions, unclear or too broad ones indicate that OPs are still struggle to learn, and may need a moment of insight to fix it. That moment needs a period of time for incubation, and it may take some months. By then, the questions may be already inaccessible from their profiles.
So while I don't disagree for deleting such questions, should we have a special treatment for them? As they don't invoke controversial (the very reason why deleted questions can only be seen in 60 days), I think it's safe to leave it accessible in future for the user to re-read it. I'm not arguing at its disappearance on the site.