Finally read the above post (been on my to read list for a bit!)
Yes. So much yes.
I have always said that in my mind the great crusade is the era of Rome on the March expanding its borders. It’s the time of Caesar Augustus and some of his less crazy relatives.
The 41st millennium is late Rome, with barbarians on every side, a fractured empire, constant power struggles and civil war and mercenaries who can can turn from soldier to invader all to quickly.
Obviously it’s a late Rome with the nastiest bits of early medieval times sprinkled in for good measure - especially with the aesthetic.
One could argue that this time of Roboute Guilliman could be almost Constantine the great sort of moment. A kinda renaissance and resurgence with a strong leader kicking butt but still simply an upswing on the general downward trajectory of the empire on a larger timescale. The imperium split in two after the eye of terror blowing up kind gives us a western eastern Rome kinda vibe as well.
On the art you posted below. It’s just beautiful ain’t it. It tells you so much about 40k in one image. This is the forty first millennium; our standard form of transport is to fly city sized cathedrals through a quite literal hell to get from one place to another. Enjoy your stay.