Aankin was destined only to destroy Palpatine. Becoming Darth Vader was not the Will of the Force. And if you believe that it is, then it can hardly be blamed on Obi-Wan, can it? That Vader was Kenobi's student was established long before there was ever a Yoda or Qui-Gon--and long before anyone blamed Obi-Wan for Anakin's choices. Lucas was a good 10 years or more away from writing TPM when ROTJ was made; the only accounting he made for the prequels was to assume he'd be making a different TPM from the one he eventually made. He started out with Obi-Wan meeting Anakin first, then replaced him with Qui-Gon. The ROTJ lines reflect the assumption that his earlier drafts would be the ones filmed. As for Jar Jar, I'm referring to his being elected Senator, and then saying let's give Palpatine emergency powers. Real smart move, that one.