Blizzard probably came up with this idea that they could charge people to change their name, I hope this isn't the case as other MMO's support changing their name for free (1 change a month).
BUT READ THIS FIRST BEFORE QUOTING ME:
People continuously say that other games copy from WoW, but nobody seems to understand that if any specific function exists in one game and another company comes up with a similar idea for theirs, It's not even copying especially since it's so hard to generate new ideas for MMO's without being criticized for copying.
My point is, this function is already in other MMO's and nobody will label this as copying an idea because it's WoW.