EU isn't euro-centric because the developers are biased, EU is euro-centric because, historically (and this is a historical game), technology was euro-centric. Despite the Chinese having a leg up on everyone, despite the Mongols taking over a bunch of the known world, despite the Aztecs and Mayans and Incas, the European powers at the time period we're dealing with had the best stuff. The Native Americans didn't magically have cannons and guns, which is why they were ultimately pushed out of their ancestral lands. They never even had the technology to produce cannons and guns, they just traded for them or looted them.
Britain and Portugal owned Hong Kong and Macau of China, respectively, because they were able to dominate trade because the Chinese lacked the capacity to do so (mostly due to their isolationist policies stagnating everything). Portugal, Spain, Britain, the Netherlands and later the United States were able to bully Japan around economically because Japan lacked the technology to really do anything against them. Heck, Portugal basically owned Nagasaki. The Middle East is no longer the jewel it once was, and North Africa has long since lost its luster. Even much later, India was subjugated with the clever use of flags (ha, Eddie Izzard). Heck, even in WW2 the West was technologically superior to the East (again with government policy, though). After considerable Western influence, though, the playing field was evened out. This is modeled rather accurately in the EU games. Everyone who isn't the West needs to Westernize if they want the best tech. Those wishing for AU history get it in pretty much everything but tech, although that can happen as well.
So yeah, before you blame the historic empire simulator for being euro-centric, blame reality.