I've heard Larry the cable guy doesn't actually talk like that, ot at least he didn't. It was just a character he played as part of his stand up that eventually he got trapped in because that's what people expected. Same for Cheech Marin to a lesser degree. I think that's kinda what happened to 40k.

Like Dan Abnett absolutely understands the satirical nature of the world he's populating but he has to give people bolter porn and imperial apologia because that's what they expect. It has gotten better in recent years and hopefully the fans will catch up eventually