There are quite a few relatively worthless and unwanted superior sigils and some inexpensive and common superior runes in the game at the moment with no use beyond vendoring or selling at the tp (often at a loss considering fees).
Unlike other exotic items, exotic upgrade components cannot be used in the mystic forge (at least for the 4 items = 1 item recipe). I would very much like to suggest allowing us to toss unwanted sigils and runes into the forge for a chance at a better, more desirable rune/sigil.