(edited by Egrimm Van Horstmann.7921)
Masteries, spread the wealth.
It would probably take a lot of work, and time, to re-do existing maps to allow some of these other Masteries. I’m guessing the Devs consider what would be more embraced by the player-base: New content, or changes to old (core) content. It seems new content is pretty popular. /shrug
Maybe we will see some of the old Masteries in the new expansion maps. One never knows. =)
Good luck.