Well, if that had been done right in the prequels, it would have worked perfectly. If you remember, most of Obi-Wan's advice and connection to Luke was based off of his mistakes as a young man. But, wait, I forgot, prequel Obi-Wan was perfect in every way and never made a mistake. But, yeah, if there had been a point in the prequels where Obi-Wan had given in to hate and came close to doing something evil, then it would have resonated well with that quote and been a contrast to Anakin, who was also confronted with choices and didn't resist.