Cobb died in July 1961. That's enough time, isn't it, that we ought to be getting a clearer view of who he was and what he did. This phenomenon first came to my attention when I was working on a major term paper on second President and major Independence mover and shaker John Adams. The earliest primary source which I read, published in 1801 (regretfully I can't recall what that was, as I wrote the paper 35 years ago and can't easily find it) and right on the heels of his Presidency thought him little but scum. But as the books and articles about him accumulated over time, it seemed that by around 1900 people were admitting that he wasn't all that bad. By the 1970s, Adams was actually rising into the camp of a 'better than average' President in the eyes of the majority of historians.
Indeed we can extrapolate this point further when referring to even newer biographies of Adams. David McCullough points out that a quote about Adams, used in the musical 1776 as a citation against the Massachusetts lawyer as 'obnoxious and disliked', can be found only in a self-description of attitudes toward him in a letter I believe to his wife Abigail. McCullough finds Adams spoken of that way by no one else. Judgment of Adams by history continues to tick upwards.
When I was still teaching, I rarely went past World War II in my lectures and assignments. My justification was that things which have happened too recently aren't history yet; we're too close to the events to think about them objectively. True, there are those history will likely never treat kindly. I can't imagine Hitler, Stalin, or Mao becoming saints over the coming decades. But it does appear that history looks kinder upon the more mainstream people and ideas as time marches on.
I do wonder if it would be fair to argue that it's not history if we've lived it. Or at least, not a full and true history.