Kleinfeld's paper On a short proof of my doctoral dissertation “On simple alternative rings without nilpotent elements” (J. Algebra, 2013) is a gem. After giving some background information, and a fourteen(!) line proof of the theorem which once upon a time earned him his doctoral degree, he writes:

Now what do we draw from this proof? First of all, I feel that Bruck was wrong to deny me access to our joint paper in claiming a dissertation. But OK, it didn’t harm me, so I can’t sue, but allowing a result which is so undeserving of a PhD dissertation puts shame on him and shame on me for not seeing how easy it is to prove this result after the Bruck/Kleinfeld result. More people to add on this list are the people at the University of Chicago, namely Kaplansky, Albert, and MacLane. Kaplansky and Albert, who had already published papers on alternative rings, had they seen such a proof, or imagined such a proof, wouldn’t have given me a post doctoral fellowship in 1951. MacLane didn’t think too much of my result because it was negative. It ruled out all examples except the octonians, and if he’d found something wrong with my thesis, he would have told me, too. Add to this list Herstein, who became a close friend. He was at the Cowles Commision at the time, but came over at any free moment to listen to lectures and talk to me at the University of Chicago. He, too, must never have seen how simple a proof there was. [...] To that list, add the editor of the Proceedings, because I published a lengthy paper consisting of my dissertation in the Proceedings in 1952[2]. Also add to the list several other algebraists who were going to put their students on writing a master’s thesis reproving my doctoral dissertation. I told them it was too easy. So shame on all of them. But no harm is done because those people I mention are not here any more.