Quote Originally Posted by Colorful View Post
I don't know why they just don't have different times for the maintenance on each datacentre, I guess it would be like back in the day with WoW how people would create alts on other regions and overpopulate those servers while their own was done.
It's because they want the expansions/patches/hotfixes/bugfixes to be applied at the same time across all of the servers. Otherwise, some servers will have an advantage(Japan servers getting new items/recipes before NA servers, or having easier drops because the hotfix is supposed to increase drop rates, etc. Or other servers will have advanced warning of things that are going to change, allowing them to abuse exploits before they're removed, stock up on items needed to create new items, etc.