From all the Anime live action movie made by Japanese, all of them are using Asian cast including with the latest live action movie of Shingeki No Kyojin. There are many uneducated westerners or maybe just angry at this fact who said the reason for that is because of
- The movie are aimed at Japanese audience so there is a language barrier issue if western cast are used.
- Japanese can't hire western cast due to Japanese lack the money.
- Etc other things only uneducated idiot can come up.
All of those are nonsense because there are movies made by Japanese which use western cast aimed at Japanese audience where some of them western cast don't even speak in Japanese language, the only difference is none of those movies are adapted from Anime which is more evidence that when it comes to Anime Japanese agreed that the characters appearances are based on Asians appearances.