There is no doubt that racism in America has greatly diminished in the past 40 years, and despite the blip in the 80s, it has continued fade. The biggest problem with racism (obviously there are others, but this is the most pernicious) is that it currently operates at an institutional level. By the latter I mean that there are practices within are social structures that continue to benefit certain groups of people over others (whom ever is the dominant group within that community, they derive the benefit).
Lets consider the process of hiring. If we take two well-qualified candidates (forget equal since there always is some type of difference), quite often people will choose the individual with whom they feel most comfortable (and why not, our "instincts" are also used to make decisions). If one's experience embeds them more in one type of culture than another, is it surprising that they will feel more comfortable with the one that is closest to theirs; thus, birds of a feather fly together. It is factors such as these that require institutions some times to implement process that encourage diversity, otherwise it is unlikely to occur by itself (or it will occur at too slow a pace).
Bringing this to the NFL
, if all owners are white older men, is it surprising they will feel more comfortable picking someone with whom they can connect? Again, is it surprising that GMs are going to pick someone that with communication is a simple process (not that it would be complicated with another subculture, it is just a question of which is perceived subconsciously as being easier).
Now take the NFL and blow it up to America at large (only it is worse in corporate America because merit is not as easily measured as it is in the sports field). On the plus side, as a culture, as we become more integrated, these issues become more moot, and their is no question that integration keeps growing. However, there will always be some form of prejudice. It is in our nature to differentiate, the problem is how the process of differentiation manifests itself in the community. Sadly, too often it is wrapped by ignorance and delivered with unreasoned hate.