Out of curiosity, would you quantify that statement? As CP has said, you're missing out on some superb writing.
For me, my first Black Library book was Horus Rising. Been devouring them since, but I have a definite preference for Space Marine action over all the other parts of the 40K-verse.
I've been enjoying a shift to the WHF-verse (for a variety of reasons, including writey-based ones) and frequently think that it's a real shame more isn't made of some of the WHF titles. Because they're really, really good. (ANYTHING by Chris Wraight, for example, the Nagash series...)
Not to mention Nathan's Ulrika series! which is fucking brilliant!!!