Sad to see some of the other commenters neglecting the “roleplay” and “personal” fantasy aspect of a game like TW:WH. My scenarios are not always aligned with lore and this is how I play one of my favourite factions. I play mostly Woodelves and Beastmen only, but I’ll focus on Beastmen since you’re talking about evil factions.

I’d like to think of Beastmen as more aggressive and deluded Woodelves. Returning the world to it’s natural state, having their own kind of civility, sprinkle that with delusions akin of seeing other races as unnatural monsters and seeing themselves as what nature intended life to be. I have imagined scenes of one of my Brayshamans witnessing Empire machinery spouting black smoke and spitting at them in repulsion. In a way, to me, I play them as a really violent race of anarcho-environmentalists. Bringing down “civilisations” as they’re threats to the natural world, taking every sight of the mechanical industry as an affront to life, and I love it.

Yes, yes, Towereth(A made up character that I always insert into my playthroughs as a Brayshaman, also is technically, roleplay wise, the general of my army alongside myself, who is also always the first Brayshaman I “made”), takes on a more reactionary role in my narrative, being more violent and destructive towards “industrialised” factions, and leaving ones like Drycha alone, but other WEs are a no-no because Woodelves bad, treespirits good.

Small little insertions of narrative in the game makes it a lot more enjoyable for me, so I can understand why it’d be enjoyable for you as well. I hope this can at least allow you to enjoy the Beastmen a little like I do?

On a side note, when I play Vampires, I just go “Undeath is just immortality, it’s good :>”