re: Are Cultural and Ethnic diversity and competency needed for success today?

It is not necessary to have "empathy" for others to succeed. Neither is it intrinsically "noble" to have friends of any particular race, religion or creed or variations thereof. Where and with whom one chooses to associate is largely value-neutral as long as one does not seek to deprive others in some way.

That said, I think that any way one chooses to broaden one's horizon is generally a good thing for personal development. It's pretty scary to me how small and insular some people's lives become. Some people just aren't curious about the world. And no matter how much you try, they have no desire to see anything beyond their own nose.