goku is more culturally recognizable than anyone in akira. goku is "the anime character" for over a billion people, i doubt akira has that much cultural reach.
talk shit about dragonball z and akira toriyama all you want, but dragonball is a cultural institution at this point. akira can't hope to have the same reach. sure it has 90s nostalgia behind it, but it was never agressively marketed as hard as dbz was. also it's easier to buy the rights to a series like dbz than a movie like akira.
it never stood a chance to begin with.