The answers to several things on here is simple.
1: Tyranids are in it in case you may want to relocate the campaign to say, Ultramar dor example. Also, don't forget those Genestealer Cults can hijack a ship, jump into warp, meet with their hive fleet and can return anywhere from a Millenia before they left to a Millenia after they left (I know, it's an exaggerations, but still). Remember, in the warp, time is nothing except the flash of the : on a chrono. Part of the reason why Warmaster Abad(feminine hygene product name here) is still young and vibrant while on the imperial side any Loyal Space Marine veterans who saw the Heresy play out are trapped in Venerable Dreadnaughts.
2: The PDF thing was already covered. Who can blame them for wanting to cover their initial investment in creating the PDFs before putting them into the pirate-ready format that is PDF? It isn't like you and your buddies sitting around creating a homebrew 40k system. They have game designers, artists, game testers, office staff etc. to pay. Not to mention producing enough profit to create an initial investment to start on their next product. They get that money by selling copies of the Books. If this was a perfect world where nobody pirated, or at least waited for older games to go out of print before they started, i'd be joining in the complaining. However, enough people do pirate to make simultaneous releases suicide to the profit margin. Without profits, quality on future releases drop or future releases are cancelled and game lines are terminated.
3: Them only going so far into detail with their Pregens? That is to make it easier for you to customize them as much as you want. It is not laziness. Look at the old AD&D... They were mostly so rigid that when they were multi-part sets that if you messed with them (Look at the Dragonlance Modules) without them being made to be messed with (Like choosing if Sturm Brightblade or one of the others Heroes of the Lance died) then you break the adventure. Would you rather see future story suppliments wind up like that?
4: The Core Book focused on a sector overview and the game mechanics. Not much time to 3D the Ruinous powers or work on building up horror when you are explaining a rebuilt from the ground up instead of a tuned up system. And Enemy Within was focused on the Hereticus. And the Hereticus focuses on the Cultists and their Views on the Gods. Plus, it is Chaos. Do you think that Khorne is going to describe every detail about his Skull Throne to his followers so the secrets can be gleamed by Tzeentch? No. They focused on the basics so that Slaanesh Cult A would be different in their approach to worship than Slaanesh Cult B so that every cult would be unique and enjoyable instead of becoming a formula like "To Stop a Slaanesh Cult's ritual before they can summon their Daemonettes you have to shoot the high priest/ess in the crotch, Break the Phallic Rod that is the center of their ritual into inch long pieces then focus on purgation of the cultists."
5: As for not showing anything at Gen Con, look at my rant on profits. With Enemy Within, I saw crappy pdf copies of it out for it on certain sites within 24 hours of the Book's release in my local store. That probably hit them hard in the pocketbook. With a hit like that, they probably got messed up on being able to start producing anything in time to show anything at Gen Con. So I say this again. Please quit the pirating.
6: It took 17 suppliments to get D.H. 1 to be the expansive as it was. Please give D.H. 2 that long to do the same thing.
Final Item: They redid D.H. as a second edition and have been making a lot of references to Rogue Traders. How long do you think it will be before Rogue Trader, Deathwatch, Black Crusade, and eventually even Only War will be getting a 2E treatment to modify them for the Askellon sector and to fit better with 2E rules? I wouldn't sweat the idea of the Deathwatch getting the Gray Knight Treatment to be fit into D.H.