MLK was not a naive man by any stretch of the imagination. He believed these words and so do I. To discount the progress of history is to discount history and focus on the narrow, limited stretch of your immediate perception.
A mere hundred years ago, an eyeblink in historical measure, there were no civil rights at all for women, minorities and homosexuals, no child labor laws, no 5 day work week, no minimum wage, no unions and on and on and on.
To deny this progress because we have not yet completely destroyed the reactionary, regressive forces of humanity, is to deny truth, to deny history and deny hope.
We will never achieve perfection, we will never vanquish those that wish dominate and enslave, but we will acheive progress, mostly incremental, and slow and hard slogged, but occasionally explosive. And there will be setbacks and defeats and steps backwards.
But history shows, all of history shows, that inevitably and without fail, we progress. If we didn't, none of us would likely be here now typing on computers and debating the efficacy of Obamacare.
Deny progress at your own peril. Wallow in cynicism and ultimately it will only dimish you, personally. The universe will continue to progress anyway and those of us that embrace it and acknowledge the progress will pass you by.