I dunno, giving Japan a pass because they're less racially diverse than the US reeks a bit of hypocrisy. Some might even argue it worse given the country's fame for xenophobia, too. Logistically, yes, it's understandable, but once you get past that, the question then becomes, "Aren't there white and brown actors that are fluent enough in Japanese to land the roles there?" My answer would probably be a mix of yes with casting not trying hard enough.
I follow a few anime VOs on Twitter (Todd Haberkorn, Kaiji Tang, and Stephanie Sheh) and occasionally they gripe about the difficulty of landing onscreen roles here. Todd actually did Ling for FMA here and also had a role in Syfy B-Movie recently, but I know Kaiji (Archer in UBW) gets some shit because he's not the typical polite asian and Steph (Orihime in Bleach) funnily got turned down by CBS because they thought she was too female, whatever the fuck that means. Either way, I only joking referenced the GitS movie even if I do feel it can get away with some technicalities due to the prevalence of cyborgs. FMA or even AoT doesn't have that luxury, the latter so in that asians are supposedly pretty rare in that world.