From one point of view - if you consider giving each role a new job as balanced.
But it also caused an imbalance. Before HW we had 2 jobs per intended main stat - Vit, Str, Dex, Int, and Mind.
HW added 1 to 3 of the 5.
There's also the issue that introducing 1 each every expansion would mean creating another type of imbalance, where 1 of the 3 playstyles of dps - ranged physical, melee, and magic - would go something like 4-6 years (assuming they continue at current pace) between getting a new job while tanks and healers each got something new every 2 years.
Really, it was going to be imbalanced regardless.
I also believe that keeping themselves beholden to 1 of each role every expansion is stifling for creativity. They should be able to do 2 dps then a tank+healer another time then 2 tanks if they want and it's an option that will work well for the game at that time.
