Making a game that's a wow clone is the perfect way to have to merge the servers as soon as the next wow expansion (or the next wow clone) hits the shelves.

It happened every single time since the inception of wow, and it will happen again with Rift, which on top of being a wow clone is also incredibly bland. At least the other wow clones (say Warhammer Online for instance) had a a good backstory and an engrossing world.