A consistent theme in innumerable great comments on DakkaDakka forum and Reddit about background writings, discussions and doodles which I've posted, is the impression of Warhammer 40'000 having been diluted down and lost its grimdark ways in later years.
Great as the discussion is, I've not got the same impression from what I've seen of 40k in the last years. To my eyes, the state of grimdark seem on the contrary to be healthier and a lot better handled than GW is often given credit for. A few observations about the general drift:
Cawl's secret army of uppity hand next level Astartes is fundamentally a rather cheesy and wish-fulfilling hope-inducing turn of events, for which I remain skeptical (despite a fondness for hidden laboratory mavericks). One thing hasn't changed since 2nd edition: Imperial Space Marines are sold as statuesque glorious heroes as an effective pull on many beginners. Still, Guilliman's impression of the rotten state of the 40k Imperium and his doubts about the Emperor stand out well as good writing, regardless of whether the 30k Imperium is actually portrayed as all that different (apart from religion) in the Horus Heresy novels.
The Sisters of Battle models took the grimdark themes further. The Penitent Engine includes an iron maiden option, and hilariously enough there is even a burning heretic husk for one of their bases.
The new Necromunda drive has been all positive from a grimdark background perspective, with novel cannibal corpse grinder cults (giving a twisted glimpse into corpse recycling for foodstuffs), lord Helmawr's giant drug smuggling operation with Ghast in the Segmentum Solar and all manner of freewheeling dark worldbuilding in the "House of..." books. Necromunda has received substantial expanded background, above what can be expected and likewise true to the demented, bonkers grimdark spirit of the setting.
According to a good friend of mine, an official story on a newly Tau-conquered Human world featured a Genestealer Cult scrambling into an uprising, since they would run a much increased risk of being detected and purged because Tau actually do something called public health care. Thereby continuing the good use of the comparatively milder-seeming Tau as a contrast reinforcer of the rest of the setting's grim darkness in general, and the dysfunctional Imperium's degeneration in particular. Tau remain an underappreciated part of 40k, despite playing up the overall horror, darkness and insanity of most all other factions by themselves seeming naïve and optimistic upstarts thinking they are building a better galaxy in a rational universe. Contrast is key, as Tolkien well knew.
Just a few observations: One would expect an excellently crafted dark setting like 40k to easily dilute and tone down its gloriously demented, cheeky regression in order to pursue a stupid illusion of wider market appeal. What instead seems to go on is a balancing act where grimdark material keeps being expanded upon true to the setting's bonkers spirit in more niche products in particular, while the cash cow and beginner bait of power armour warriors keep being portayed as noble heroes in general to draw people in with a fancy facade and eventually immerse themselves in the grimdark bounty of the wider setting.
Healthy signs, all considered. It could have been a lot worse handled.