I personally think Logia's intangibility may not be pointless from writing perspective/plot-wise, but not so far from it.
Instead of moderating the body, Oda could just let them dodge and literally nothing changes. This body-moderating thing may be eye-catching at the first time but can get old quick because it's not really interesting and the method you use against it remain the same for every logia.
It serves little purpose at best.
Unless Oda can pull clever tricks like faking death, etc. like Araki has done, and making various use of each logia's intangibility. Which is why I want to wait for the next fight before conclusion.
It's all about how Oda will handle it.
Again, we don't know if Luffy's training was really hellish or a walk in the park, but I doubt it'll ever be deeply explored; Oda doesn't care about trainings, he likes to be straightforward and charge directly into the fights with the training taking place off-panel, even off-plot. That's his style, and it's perfectly valid.
Letting readers know or not if the point, if you are a good writer. What readers feel is what counts.
A not-so-good example would be how Giorno's gang gained the Requiem ability for him. They went through hell literally to achieve it and the readers can feel their effort. Gold Experience Requiem is still too much though.
Anyways; I do think a little more emphasis on the difficulty of mastering haki could've been made. Make it so learning haki to the full extent is a massive effort that demands A LOT to learn it, to the point of risking one's life.
Everyone in AL knows haki, one with talent like Luffy can learn faster. He had special training, sure, but I doubt it cost him anything much other than 2 years.
