The fact that the marriage was not challenged at the time, and a dispensation granted in the event of one by the legitimate authority to do so does not seem to interest Mr. Hicks. It didn't interest Henry VIII almost fifty years later, but he was in a better position to rewrite history.
Back to charisma; at least part of it is charm, which Hitler certainly did not have (most people in the inner circle were bored by him in social situations. It's astonishing how "charming" you can find a person who has literal power of life and death over you, though), Richard has kept legions of people interested enough to devote years to proving his innocence on the basis of what they assume was his character: loyal, brave, romantic (there is a cottage industry hellbent for leather on making the Neville marriage a love match. Which I hope it was, but let's face it . . .) Marie Antoinette has it as well, although Andre Castelot once wrote that he doubted you could find a thousand Frenchmen in 1793 who shared the current devotion to the Queen). Part of the charisma may stem from a sentimental transformation of the victim --- and it is usually a victim --- into a figure that would have been unrecognizable to his/her contemporaries --- although in Richard's case, he really was beloved in the North, and they were loyal enough to York to participate in more than one uprising.
I am writing this while occasionally gazing upon my class taking a makeup examination. 24 out of 26 failed the first go-round, with the two survivors getting "A". This allowed me to point out to the rest that they were screwed. Clearly I had taught the material. To which one of them cheerfully replied, "Yes, but not in a way we understood!"
The story of my life.
Simon