Diversity programs are important because they uncover and fight discrimination, both explicit and more subtle.
A specific example: I once worked in a job where the team leader and hiring manager was looking at resumes, found one was female and put it aside saying "she'll just get pregnant and leave". That was an extremely explicit form of discrimination that a formal diversity program may have helped combat (eg: he may have said "oh she'll just get pregnant and leave but I have to interview her anyway to get diversity points").
Interestingly, his team was extremely uniform ethnically too, and after he was asked to leave it became much more diverse.
Edit: Oh, and to address your points about the success of Jews in the fashion industries and Blacks in the NFL: overrepresentation is not a problem except in the case of whites because of history. If it becomes a problem the other way, then yes, it should be dealt with then. It is very far from that point at the moment, though.
(White, Anglo-Saxon male here)