Akira was, obviously, the launch off point for Anime in the west, and the movie was great. But later on I read the Manga, and they were so much richer than the movie. It seems like a 12-episode Anime would be perfect for Akira. And it would probably be successful, because everybody knows/loves it.
20th Century Boys is a bit... odder. I've read the Manga twice, and I know that there's a live action film, but the work seems so much better suited to Anime. I don't know how it's held up -- certainly no one on KIA2 mentions it. It's also not great -- the build up is fantastic, but the denouement is... odd.
Just wondering if there's a reason for this, or if it's just an historical quirk.
The film was a crude abbreviation of the manga from what I can recall of reading it decades ago.
I'll agree that we ought to leave well enough alone and don't really want to see it revisited by the demons of the modern era.