Unfortunately they have to IP block areas that have licensed the game to a different publisher.
The EU + NA / Russia / Asia are usually given different servers because of language barriers amongst other reasons. I know for a fact I could easily pick up enough of the language to play a MMO with a different germanic language, but i’d be utterly lost trying to read Cyrillic or one of the forms of Chinese since they are completely alien in grammar and alphabet. Plus, because of distances geographically, you usually get very slow connections between these areas.