Agreed, especially the last two I've been feeling for a long time now. It sucks to have such a well-built world and gather all these historic characters like Kidd, Marco, and Law to one event, only for them to have no significant influence on the plot or payoff to their individual motivations.

With Luffy, what bothers me most is his endurance. He gets KO'd or severely wounded multiple times in an arc, yet gets back up a few minutes later with his "haki bloomed" every time. At this point his fights seem so artificial to me because he can just keep fighting forever and get as many powerups as necessary until he wins. The stakes feel lower than ever around Luffy and Kaido now.