Oh I like the dark. The darkness is very important for 40k.

A massive difference between old and current 40k is the amount of mystery and vagueness that existed in Oldhammer. The Primarchs were dead and gone. Everything about the Emperor was a question mark. There were only the smallest snippets of fluff about the Horus Heresy.

It created a particular tone about a universe where the glory of the past was long ago and never coming back. The current universe was sinking stagnation and fighting an eternal fight after humanity had already gotten to the “bad ending”.

Modern 40k has had the Horus Heresy novels, which replace the classy vagueness and mystery with detailed play by plays. Perhaps characters inside the universe don’t know about the details, but we as the audience do, and that changes the entire tone. Rather than Primarchs, the Emperor, and the Heresy having tantalizing rare clues scattered in the lore, you have thousands of detailed pages to explain them all.

Now with Guilliman back, the stagnation is gone and the door to flooding the setting back with Primarchs is open. Every single Little Timmy is screaming that they want their favorite primarch to show up. The setting has this distinctly power rangers and plot moving forward kind of vibe, which is completely opposite to the stagnation of eternal war.