I remember asking about a clone feature when XF first started, and I went on mentioning it for s while but it faded out on me.
This is one of the few things I miss from VB. When making a new category or forum, I could select an existing one as a template, rename it, then tweak it sljghtly if necessary. Very useful.
'Cloning' forums is something that I miss from phpBB when I moved over to Xenforo. On phpBB when setting up a new forum you had the option of copying the permissions from an existing forum to the new one. I know that Xenforo lets child nodes inherit permissions from the parent but you can't do this for other nodes.
Inheriting permissions is a big part of it, but also things like doing a copy and paste on the description, adding the order etc
VB had it so easy - a dropdown to select the forum or category then just change the name and you're done.
a mega addition would be batch clone - with an initial default naming convention of same name plus a numeral.