When Ace died he made Luffy understand that he was not that strong and he made Sabo remember him and Luffy so i think that just was asome! ╮( ̄▽ ̄)╭ (i'm still crying about it (╥﹏╥)
Ace dead was good for the plot and for Luffy's character development. I was upset about it but I wouldn't change it. I actually feel more sorry for his comrades who lost a father, a brother and so much more trying to save him.
rai T T... The doc did something didn't he.