RJ said he created Rose because he felt Finn and Poe had the same voice, but imagine the Rose and Finn conversation about war, but Poe took Finn’s place and Finn took Rose’s place. Poe likes being the hero and does whatever he can to win, but considering Finn is a literal child soldier, he knows all about the costs of war.
Rose is not talking to Finn about how bad war is. She’s talking about how war against the First Order is good, justified and necessary, and that Canto Bight is awful for supporting the First Order, not for supporting war.
In that case, why does Rose save Finn from killing himself for no purpose? Wasn’t the point of her speech to inspire him to fight against the First Order?
Yes, I know common sense don’t sacrifice yourself for no reason, but it would be a much clearer telling of the theme if you had the character learn about it and then react accordingly, not learn about it and overdo it to the point the same character who inspired you to do it now tells you a new message… right at the climax?