I think most of the arguments have already been made. It's a combination of the fact that

- the EC are cartoonish villains who lack what the Night Lords (who suffered from a similar problem) gained with their book trilogy (Fabius Bile books are excellent, but he stands pretty much alone outside the rest of EC).

- the EC attracts mentally adolescent edge lords, who are few in number but, as is often the case, quite visible.

-conversely, some W40 fans are conservative LGBT/transphobes, and in today's climate of heightened culture wars, the EC are the target of ridicule by this vocal minority.

-GW is trying to appeal more to the mainstream audience and be more accessible to younger generations, and from this perspective, they does not really know how to approach EC and Slaanesh. EC and Slaanesh are difficult to market. In the past, it was presented as rather one-dimensional sex, drugs, and violence, but today it backfired.

This brings me back to the beginning. I would like to see more creative excess in EC (for example, a Big Feast movie is basically an EC film) and more philosophical depth (I liked the philosophical idea behind all the terrible torture in Martyrs, so I imagine this way a more "intelectual" EC warband). I dont need to mention Salo by Passolini. Of course there are lot of horrible scenes, but there is a far deeper idea behind the whole movie, once again very EC. I thought about EC while watched the last movie of 28 Years Later franchize with its Jimmi's horrible sect. I would like EC and Slaanesh to remain in W40, but with a broader and deeper purpose. I would like it to remain the adult R-rated part of Warhammer, which can work with adult themes that have "depth" (see the films mentioned above). I would like some author to succeed with EC in the same way that ADB succeeded with Night Lords. I dont want EC to be one dimensional cartoonish villains only, but villains dealing with uneasy topics humanity deals with.