I think they split the regions just for ease in the competitive community, like I think it'd be pretty hard to arrange competitive events that use the ladder as part of the qualifier if they had to use a global ladder and then pick out which players are located in specific regions, etc.

However, I find it stupid that you can't transfer your gold/dust/cards from region to region, essentially giving you a "global account" without a global ladder ranking. That's just annoying and stupid.

My video card is slowly dying so I guess I'll be pulling away from PoE and League and playing this more.