I'm sure it has nothing to do with campaign and seniority rules that heavily favor incumbents in terms of money and recognition. Oh, and who writes those rules? Yep...them in power.
Ironically, when Byrd was elected the first time, and through the first twenty years or so of his time on the public dime, he would not have crossed the street to talk to a man the color of our current president, much less shake his hand. I guess the positive spin is that it means there is hope for all of us, if we live long enough, to reconsider the stupid things we do and say when we're very young and very ambitious.