A few reasons. A lot of the KR stuff is handled differently.
Also the Asian WoW subs are a lot more unstable than EU/NA. There were global sub losses last expansion, but the vast vast majority of them were in the Asian regions. So the company that manages WoW over there, and Blizzard, are more likely to cater to the demands of that region to get the WoW population stable there.
This was a needed thing in that region, response to it will likely be positive. In the western market however when an MMO starts merging servers it's seen as a sign of doom as most MMOs start merging servers when they've failed. You can already see a good example of that in this thread with people posting things like "So down from total 26 to only 12, wow." - It doesn't matter why the mergers happen (People flock to a handful of servers and leave the other servers more or less empty." - It's seen as a sign of failure.