Currently, when you delete the first post of a topic, only that post is deleted. In some cases, this could be desired (I cannot think of any, but I'm sure someone, somewhere could). However, in most cases all this does is destroys the flow of the topic by removing the original content. Now all the rest of the posts in the topic make no sense, as there is no context.

In such a case, I would personally end up either trying to restore the deleted post from a backup or deleting the rest of the topic anyway, so this would just remove a step.

In my opinion, we should add a new check box on the deletion screen that defaults to unchecked (so they don't accidentally delete a whole thread) and asks "Delete entire topic?" only when deleting the first post.

Of course, we would probably want to disable this if the user is not a moderator because otherwise a user can destroy their own topics if given permission.

Related: when soft delete is finished, it should be behave the same way; the topic should be soft deleted, not just the first post.