Just a hunch: if the boxes are ever recovered they will show that the pilots were overcome by some sort of toxic fumes, that the origin and nature of these fumes will remain a mystery. Malaysian Airlines and the way whatever cargo aboard was handled will be blameless. Ditto for Boeing. Ditto fort the pilots, who will be remembered as professionals who attempted to save their jet, and the passengers, in impossible circumstances.
Will this be the truth? Perhaps. But, given the various reputations and commercial interests at stake, the question merits asking.
Remember Habsheim.
http://www.crashdehabsheim.net/CRenglish%20phot.pdf