Well, two things happen to me. 1) I accidentally close a window, then have to recall the type of formatting it had, and reload it.
2) I'm on the wrong window when typing a symbol and it overwrites the 'perm' symbol that's there. ES, $tick, whatever.
Don't see any downside to optionally (per window) asking if you really want to close/modify the symbol. You can probably limit the query to just those two, as any other change would most likely be deliberate.