User blog comment:LuffyPirateKing/Mr. 3 killing Ace/@comment-4493594-20111026171936

Luffy and Roger smiled when they were about to be executed because they had no regrets. Roger because he had accomplished all he wanted to accomplish and Luffy... well, I don't know. He's a hopeless optimist, I guess.

Either way, having no regrets did not apply to Ace. He had regrets. He wasn't ready to die, knowing that his brother was out there fighting an overwhelming amount of powerful enemies.