Re: "I wanted to kill off Robin as soon as I started writing Batman." I thing it likely that the part he found repugnant was less the "kill Robin" thing and more the "let the public decide whether Robin should be killed" thing.
Some think the "public poll" section made something bad much worse. The miniseries "Bratpack" parodied this in the first issue of Bratpack. A radio show polls the audience if a team of sidekicks should get killed off. Then a villain kills off the team of sidekicks.