what the hell, if you don;t think luffy has gotten stronger you've missed the whole goal of one piece.
Luffy wants to be the pirate king. He is constantly getting closer to his goal.
Luffy must first overcome the shikabuchai, which has consistantly done and next measure up to the four great emporers or whatever, which he will have to do. and of course find one piece
in order to fuful his goal he must get stronger. He is doing just this. yay him. end of story.
another thing to support my argument.
-the luffy now could kick the past luffy's ass.