Originally, the World Pass system was introduced to maintain a balance among all the Worlds and prevent overpopulation. However, with the continued stablization of each World's adventurer community and recent technical advances in server technology, it has been determined that allowing players to create new characters on Worlds of their choice would not greatly affect the current population balance.
Pardon the continued cynicism, but this is a more true paraphrase of what was said above:

"We have driven off so many players that the population of each server has dropped significantly. In addition, the influx of new players has slowed to the point that we no longer fear a surge in any particular server population. Due to these factors we believe it will be safe to allow players to choose their servers without the World Pass system."

Most of the amazing things SE is FINALLY doing for the game sound like nothing more than desperate near death throes to me.