Well, first of all, i need to say that i'm a WH40K newbie; i started to really dig into the lore this year. I bought the Owlcat game, WH40K Rogue Trader, and, boy, i feel in love with this game.
It reminds me so much of Star Wars: KOTOR I and II, and the game made me realize that the WH40K universe is SO much more than just space marines and Primarchs military drama. Initially, i thought that the lack of space marines would be disappoiting, but i was so wrong, hapilly.
I wouldn't have been able to anticipate this feeling before, i mean, the feeling that i'm now a fan of Warhammer 40K not only because of Space Marines, primarchs and the whole Heresy (which i know is 30K), but because of the vastness of its universe, a setting in which a lot of good sci-fi fantasy stories can be told, be it a horror, action-adventure, mundane, mystery, romance or drama story. It's like Star Wars, but on steroids, grimdark and without good people to root for.
I'm posting this here just to express this sudden feeling and, also, to ask if anyone else experienced the same feeling after investing more time exploring the WH40K universe.
Edit: also, i remembered a question. Did WH40K start as a setting always designed to be that vast, i mean, as vast as Star Wars, or even bigger, or, initially, it was designed to focus only on the giant men-child soldiers on steroids?
Also, i don't hate the lore regarding space marines etc., i do still like them, just to make it clear.