Really with the stress of one's job, family, children, friends, the government, caffeinated drinks, alcohol etc., you think blue light is your problem with sleep?
What we think our problem is with sleep doesn't matter. It is what Apple wants to help us with - with what is under their direct control and something that we use - their hardware. Simple.
They are trying to eliminate one thing that could and does affect our sleep - that is light. And artificial light of the displays, at that. Why would you be so negative about a good thing that actually helps you so directly, yet so subtly? It is not as if they are letting users choose the hue they want to explore their creativity that one could construe this as a gimmick. This one is actually pretty good a feature to have.