Why shoot colour, when you can shoot black and white?
But no one does this. I love black and white, and hoarded a lot of Kodak's 35mm bw stock when they were getting rid of it. Films like The Man Who Wasn't There show that you can shoot good black and white films today.
They just aren't realistic. They are self-consciously stylized. And they aren't popular.
I feel like that is how "flat" films (non 3D) or "blurry" films (24fps) will be seen in the future. Much like we have "silent" films. Isn't that label judgemental? Why call them silent, when we should really be calling all the rest "talkies", since those came second? But that's the way the progression goes.