yes, I agree with pretty much everything in your post. It clearly is about audience, or market. Your rules also clear and well thought out. I don't envy you reading so many turgid PhDs. When I (rarely) read academic articles I do find some of them unbelievably turgidly written. Interesting though that Amand Foreman's book "Georgiana, Duchess of Devonshire" was essentially a re-written PhD. It broke new historical ground and found a mass market, so such things OUGHT to be possible more often...