OK, first of all, I think most of us agree with the fact that live action adaptation of anime/manga had been suck until now. However, looking at some anime/manga titles, I think there is potential for them to be a good live action movie if they are properly created. There are a lot of room for discussion but I'm going to make it as simple as possible.
I would use Fullmetal Alchemist for an example. Why?
1. Story - The story is very good and well developed. For this to become a success, the author must be the scriptwriter of the movie. The writer is the one who understand the most how the characters should be and how the setting looks like. It's something like J.K. Rowling being the integral part of Harry Potter development. She picked the actors and decide how the whole story would be shown in the big screen. The author at least should pick the director by himself.[/font][/color]
2. Settings - Since it is based on western culture, it is more appealing to the western people. I'm not saying Japanese culture (majority of manga setting) is not famous, I'm sure a lot of people want to know more about Japan. But it's just that people recognize western setting a lot easier, thus it is easier for the movie to penetrate the western market. Also, I think the eastern part would understand if the actors are mainly western because they are actually based on western culture.
3. Characters - Since it is based on western culture, Hollywood is a massive pool for actors. We rarely see Asian face in the manga (other than those from Xing country) so it is easier to find world class actors who can fill the Asian role. For example, Zhang Ziyi as Lan Fan (just example! =p)
4. The concept - For me, FMA has a very unique concept. Alchemy as the most advanced technology, how they use alchemy as weapon rather than how alchemy used in real world, wide range of alchemist abilities, the characteristics of the antagonists and homunculus. These are not part of your everyday concept in the cinema.
5. Special effect - We are living in HD era where lousy movie looks good when it's 3D. There aren't many sophisticated and "that-looks-impossible" effects in the manga. Looking at current 3D technology where we hardly can differentiate between reality or fiction, I don't think bringing FMA to live is impossible. Transformers looks impossible for me.
6. The popularity - FMA even had been nominated for New York Times Best Manga List. If New York Times even acknowledged it, I think the major population of the western people would have slight idea about it.
The reasons above I think more than enough to say FMA has a lot of potential to be brought into live action.
However, there is one drawback which is comedy. We all know that comedy in manga typically is a form of exaggeration. It is rarely something that can be done in real life. FMA is famous for its balance of action and comedy, so for those people who really understand about FMA, this might be a drawback if the comedy is not delivered properly in the movie.
I think I've explained my perspective. Feel free to write your opinion about it, I might missed something and I would love to discuss it. I just feel that with the current technology and available resources, anime adaptation movie can be a lot better than the previous ones.
If you have any suggestion on potential anime for live action, feel free to leave your opinion. I would like to know more potential anime which might blow our mind in the future. =)