Which means that Blizzard has provided enjoyable content. Which undermines your argument that the boost needs to be free to by pass the non enjoyable content. Blizzard can not control when each individual customer decides they no longer enjoy certain content, and it is quite laughable that you are suggestion that they are required to create content so everyone enjoys it 100% of the time from now until they stop offering the product.
Allowing players to skip content by purchasing WoD or paying $60 is removing the mandatory need for players to play through leveling content. If you don't have to do something, how is it still mandatory? By every definition of the word in the English language it is no longer mandatory for people to go through leveling content.