Working with numerous docs open it's very easy to accidentally close files without saving. This is especially the case if you're dragging a lot of files from other windows into your main document. Indeed it is a user error, but one that, at least in the way I work in PS, is a mistake that I make from time to time and is massively frustrating. I work fast and muscle memory is usually to blame.
It is especially frustrating when you do this, and close Photoshop with the thought... I can just grab the auto-recover... awesome. Nope. it was deleted. I understand that we can't stockpile large auto-recover files indefinitely, but immediately deleting the file on close is not great. give it a day or a week or let the user define the time period.