It wasn't because people were admitting the most qualified...
Actually, as a supporter of affirmative action, I disagree with that.
The justification for affirmative action is that the system is biased all the way through. By the time you show up for a job interview, you are the product of a multi-year system that is biased at every stage. Quality of home life, quality of early education, progress through the university system, through social networks, work opportunities provided by families and friends, all lead up to that day that you are sitting there in the job interview hoping to get that leg up.
The principle behind affirmative action is that in a system that is biased at every point, you have to correct that bias at every point.
Which is a very different principle than saying that it is simply there to counter-act unfair hiring practices. That misses the real point. Maybe we are all born equal, but from about five minutes after that, things are anything but equal. Affirmative action is meant to address that.
Another principle behind it is that so long as the entire system remains racially distorted, it will continue to be biased. That unless the people who make up the system reflect the racial mix, there will be inherent biases remaining. So, even if in the short term affirmative actions means not always hiring the best person for the job, it will result in a more effective and efficient society in the long run. In the long run, it really is a waste of human capital to shut out entire segments of the population. But sometimes you need short term pain to achieve the sort of long-term gain that implies.
What is the long-term impact of changing the perception that a certain racial group cannot make good school teachers? Or lawyers? I would say that the long-term benefit of that massively outweights the cost of having slightly worse lawyers and teachers. Affirmative action created role models, even if perhaps those models weren't always the best people for the job. The generation that followed benefited tremendously from that--from the elimination of race as a factor. Huge.
So the principle of affirmative action really is to give a leg up to someone who is qualified, but who might not be the most qualified, in service of a greater good.
That's an uncomfortable discussion to have because lots of people inherently believe that the best person should get the job -- but when the best person is the product of a biased system, it really just isn't all that simple.
Anyone who thinks race relations, gender equity, etc., is a simple problem, easily fixed by the imposition of some simple procedure, is dreaming. These are hard problems, the solutions are imperfect, but better than no solutions at all.
And I believe it has worked--affirmative action started a few decades ago, and we probably put a few losers into jobs over the years--but these days there is a LOT less bias than there used to be, as a result less need for affirmative action. But I think that is a consequence of us having implemented it, and suffered through 20 years of it, to get to a point where the best person for the job really might be a minority and affirmative action is no longer needed. Well it's probably still needed--but we have seen some progress.
In the organization I work for these days it is a non issue. In theory we subscribe to those principles in our hiring practices. In reality we don't have to implement quotas because just hiring the best person for the job has resulted in a pretty diverse racial mix. Once upon a time that might not have been so -- but it is now, and I really think, thanks to the affirmative action programs of the past.