SM2 is not thay grimdark because it follows a space marine. Darktide has all the grimy grimdark of the foot soldiers with servitors glitching out and begging for death, or just crappy hive life.
Rogue Trader has the whole "wasteful bureucracy" grimdark done well, especially with genestealer dlc where you explore a ship's underbelly.

Wby the fuck are we nitpicking a game centered around space marines not being grimdark enough?
That's like watching a SEALS or Delta team going on a mission in an active warzone and complaining its not grimdark because we dont see corrupt politicians killing hookers or fentanyl hobos roaming the streets riddled with crime.
The fact I need to say this is insane.