Just had a thought, since the new post mod 16 artifacts will have more stats, as far as I understand anyway, the older artifacts will become defunct over time. Which is all part of life's rich tapestry. However the class sigils were intended to get people to play other classes, level new toons etc. to obtain the artifct associated with them. If those artifacts become defunct and undesirable... that motivation will disappear.
No idea what my toon is now.