https://www.warhammer-community.com/2017/11/17/new-40k-faqs-need-know/
It isn't often these days Dark Eldar are mentioned in anything from GW, but - as expected - GW has made mention that they believe the Ynnari nurf is appropriate given the changes seen in the Craftworld Eldar codex, as well as what we can expect in the Drukhari and Harlequin codexes to come.
It is a little bit of a touchy subject surrounding the Ynnari nurf (rightfully so), but personally...this very, very small mention of why GW thought it important to 'nurf' Ynnari makes me happy and is in line with what I anticipated to be the reason for the nurf.
As a Dark Eldar purist, I'm not very interested in Ynnari, and I would hate for GW to run with the notion that "sure Dark Eldar don't have access to ______, but we have given them the Ynnari, and so they can follow the Ynnari path if they really need ______."
It lends itself to Harlequins and Dark Eldar possibly seeing complete codexes. Tyranids' codex is very much what I would like to be the closest approximation to what we see implemented. It is a very well-rounded army, complete with efficient ranged, melee, psychic (obviously not us), and versatile units.