Why is Martin Luther King's message on the military-industrial complex, society, war less known?

I have recently been learning more about King after I received an email from someone I know. From my classes in High School I learned the basics leader of the civil rights movement, against Vietnam war, etc. After I got this email from this person I read further into the nonviolence and all. I was shocked to learn about King’s message about the military-industrial complex, and this very insightful quote from a speech

“I want to say to you as I move to my conclusion, as we talk about “Where do we go from here?” that we must honestly face the fact that the movement must address itself to the question of restructuring the whole of American society. (Yes) There are forty million poor people here, and one day we must ask the question, “Why are there forty million poor people in America?” And when you begin to ask that question, you are raising a question about the economic system, about a broader distribution of wealth. When you ask that question, you begin to question the capitalistic economy. (Yes) And I’m simply saying that more and more, we’ve got to begin to ask questions about the whole society. We are called upon to help the discouraged beggars in life’s marketplace. (Yes) But one day we must come to see that an edifice which produces beggars needs restructuring. (All right) It means that questions must be raised. And you see, my friends, when you deal with this you begin to ask the question, “Who owns the oil?” (Yes) You begin to ask the question, “Who owns the iron ore?” (Yes) You begin to ask the question, “Why is it that people have to pay water bills in a world that’s two-thirds water?” (All right) These are words that must be said. (All right)”