A couple of causes for the lack of attention on the Korean war spring to mind.

It has only been in the past decade or so that many of the key sources on the Chinese/Soviet side have been released, so unless you are (like me) interested in Diplomatic/International History, for a long time there was little enough source material for a grand history of the war, given the near complete lack of material from the DPRK.

From the American perspective, the fact that the war was an ignominious draw, where after the first year combat got bogged down into attritional warfare also plays a part. WWII is very marketable as a heroic tale, 2 years of alternately baking and freezing trench warfare isn't. Compare it with the two aspects of the war that gained some traction in the US psyche, the air war, with the first jet to jet combat, and the spy war, with the origins of the idea of brain-washing.

Max Hasting's book covers the military history of the war quite capably, but unless your looking into how it validated key American policy documents such as NSC-68 and the containment theory it proposed its social and political consequences were comparatively small, at least for the US. It had a huge effect on Japan and Hong Kong for example, in terms of stimulating their postwar political and economic development, but the mainstream appeal of that sort of book is slim.