Diablo III, you see, does not speak their language. Meet Error 84.
Blizzard decided not to allow players the ability to change their language and instead released the game with language locks. That means that players who live in Asia must currently play the game in their region's lingo.
When players attempt to download, say, an English client, Diablo III gives this message: "The client does not match the account's native language. Please use the game's original client. (Error_84)"
Blizzard players living outside English speaking countries will be familiar with this. Blizzard separates its games on various servers across the globe, grouping them by region and language.
As Sunberry on the Battle.net forums pointed out, Diablo III is apparently locked to Traditional Chinese, even for some players who live in Mainland China and who use Simplified Chinese. Traditional Chinese and Simplified Chinese are not the same.
What's more, there are many players who live in Asia and might not be proficient enough in the local language. Or maybe they'd just rather play in their native tongue. For those, they should pick up the international version of the game so they don't end up with a language they don't want to play in. That doesn't help those who purchased the digital version before launch.
Blizzard obviously blocked English on local editions, which are priced less due to the exchange rate. Shame players in those regions feel like they're being pushed for language proficiency—or lack thereof.