Logia-type defence is pretty much letting the attack go through them, no?
Ace had to block the attack with his body, and not let it go through since it was Luffy he was defending. Though it pisses me off, to say the least, that the whole death of Ace was in part (pretty damn large part too) caused by Luffy getting distracted by a bit of paper* ... while an Admiral was attacking.
I can only assume after big fight scenes Luffy starts blaming himself (rightly so!) for Ace's death.