Sometimes you do want something specific. I can understand if someone just asked for a person x, y, z and then gets a broader selection of men, women, young, old, black or white. But if one asks for a middle-aged white man, I would not expect it to respond with a young, Black women, just to have variety. I'd expect other non-stated variables to be varied. It's like asking for a scene of specifically leafy green trees, then I would not expect to see a whole lot of leafless trees.