Exactly. I don't get the hate for the Orruk Warclans book. As you point out it's really two separate army books in one, with a couple of pages added to allow the "soup" army of Big Waaagh. Moving from my old Ironjawz list to my current Orruk Warclans: Ironjawz list had no negative impact on how I play the game. I choose not to take Bonesplitterz, but I never feel like I'm missing out on something.
We don't know how the new edition of it will work, but chances are, it will be 3 different army lists, Bonesplitterz, Ironjawz and Kruelboyz and a couple of pages with rules to take them all together with it's own advantages and disadvantages.
So if someone wants to just focus on and play only with Kruelboyz, history suggests they will be able to do this and GW community even said this would be the case.