But he has all of the factors of a Logia. His body becomes said element, he makes said element. And if Oda made him smarter, I'm sure he could control said element. It's just that it is not a real element. More like a subelement, but he is still a logia in relation to it.
he becomes said element in teh same way mr 1 picking his nose and throwing bogey would.
I dunno why you brought up that first point, but our chemist friend earlier said that vulcanization can be reversed.
As for Zoro vs Mr. 1, that was a different case at a different time. We hadn't seen how powerful enemies on the Grand Line could be; it wasn't until Jaya and Ao Kiji's appearance that it was put into perspective. We have men like Whitebeard who is still the World's Strongest even hooked up to dialsysis, and Ao Kiji decimated the Strawhats without breaking a sweat. It wouldn't make any sense at all for luffy to just be able to beat these people because of the power of his heart or some cheesy crap like that.
In Zoro vs. Mr. 1, Zoro sees an unbeatable opponent; how can he beat a man made out of steel if he can't cut it? He "surpassed himself" in a similar way, but it was much faster. And now that I think about it, it was kinda cheesy how he suddenly remembered that little bit with his sensei.
Zoro got stronger and got a new ability, this if Luffy getting stronger with a new ablity though hopefully an irreversible one. you have to think that for luffy to beat everyone with his current abilities just on the strenghth of his heart would be a tad lame to say the least so he has to visibly evolve at some stage and where better to reach the next level than in the goverments strong hold? i mean let's be honest, even Franky had the better of Luffy so who the hell was he gonna protect? a stronger luffy has been due for a long time and a real visible evolution is the best way to do it without a timejump. if the strawhats can't beat CP9 individually they have no hope on the rest of the grandline.
but to counter the need to evolve thing, if Whitebeards abilities are that superior to everyone else's and he was equal in strength to a normal human with no devil fruit ability then Luffy can overcome CP9, Aokiji and Whitebeard with heart, drive and battle wits.