AAQ: All that you have told me is that since you are not allowed to insult someone, sensitivites count. Well, to me that is pretty obvious,: if the person won’t be insulted, you can say it. The other example was 2 different methods of chinuch. Pick your approach. (I am not condoning all approaches to chinuch, just that this was the justification.)
With regard to your reply to my question of which posek changed this halacha, you didn’t answer the question. Also, the examples that you brought are not relevant. With regard to Kesubah, the takanas chachamim was that there should be a Kesubah, not how the Kesubah should be handled. That was based on custom. With regard to Shemen Akum, it is still assur. they were only matir it for that year.