Maybe a player with full CT/myth/coil gear won't bother with these dungeons but a fresh lvl 50 or people who are still working on their sub-classes gear will have more options to get their gears/tomes.

I think the new dungeons will probably be used to farm myth and the new upcoming tomes, maybe it will also drop ilvl60~80 gear(?). More options are always welcome because it makes the farm less boring.