Wraithknights where created because, shock, Eldar have always had knights. Adding them in as a Wraith unit just allowed them to continue with a recognised theme. And I'd wait and see what this new codex is before judging whether it invalidates a book that quite frankly was lack luster anyway, it introduced what, one higher power Spiritseer and a couple of half way decent pieces of wargear.
Wondering if that's gonna be a theme, barely altered army listing and formations along with unique wargear and war lord traits for each of the major Craftworlds.