Here's the problem I've got: Zac Effron is Zac Effron. When I look at a screen he's on, there's Zac Effron. I don't necessarily think he's a bad actor, but his image is so invasive in everyday life that I can't see a character he plays, regardless of his talent or lack thereof.
Unfortunately the same goes for Morgan Freeman. He's Morgan Freeman. Everyone know who he is, and despite the fact that he's an amazing actor, it takes a lot to get away from the idea that he is Morgan Freeman. These translate well as voices for animated features and such, but often don't translate in adaptations of other works.
An example: I was sitting with a friend watching Eternal Sunshine of the Spotless Mind. Elijah Wood's character comes up and she immediately says "Frodo!" You get the point.
So no, I don't want to see either of those actors in Akira. I want to see actors I don't know and can't think of outside of their roles. Also, I kind of object to the necessity of a live action Akira.