Yeah it is pretty funny how people expect that every country should be well represented when why should those countries or people from them really care about MMA?
The UFC is by far the only real legit MMA organization anymore and it has a fairly non existent role in Asian countries as well as many others. It is like asking why are there no good African fighters? Because Africa like Asia don't care about the UFC, the majority of people don't watch it and kids etc don't grow up wanting to be MMA fighters. Hard to be the best MMA fighter in the world when you grow up not even knowing what MMA is(by the North American standard anyways).
It is like what the UFC was years ago, full of the equivalent of bar room brawlers. The sport took off in North America, money got involved and now we are seeing far better athletes getting involved in the sport.
All this stuff takes time and barring some sort of set back there will be great fighters from all across the globe. We are talking years if not decades though not days or months even from where we are at now. Especially with the demise of Pride and now Dream it is no wonder we aren't seeing much for new life coming from Asian fighters. It is actually becoming more difficult to be successful in MMA over there so fewer people are entering into it.