Why is the movie so shit in comparison with the manga?
I mean just look at this shit
Or how strong of a leader Kaneda is
Akira's popularity stems from it's fidelity, not it's plot. It's plot is excellent, because the manga it takes from is also excellent, though due to it being a movie it obviously can't compare.
Akira came out in 1988, and even by today's standards the animation is top notch.