My initial instinct was to say that it would lead to confusion, much like
deletion in IMAP mail folders. After a second thought, I realised it would
be an essential feature to some, so should probably be implemented as a
plug-in. Think of it as thought it was tab snapback in Mozilla Firefox.
There is one additional concern which is privacy, which is the cost of
having an extra layer to deletion. Trash can annoy the user sometimes
because they facilitate a two-tiered deletion, despite a confirmation
prompt, which makes it three-tiered..