This culminates in the Lvl 60 quest when opening up all 14 light and dark chakras enables you to do something you can't otherwise do with just having one set of 7 chakras open.

As of the Lvl 70 quest, Widargelt is still trying to figure out how to get all 14 chakra open without having to have the two different sects fight each other in live combat situations (since that's really dangerous). I would not be surprised to see the topic be dealt with again in coming expansions.