ok i cant be bothered waiting for you to answer this, anyway you're wrong in that it is well designed; because i can logically get to the conclusion that it isn't.
because the skilltree structure is the same for every class, it assumes every class has skill that are equally balanced at any given tier. this is a logical fallacy; for when balancing asymmetrical skills, you cannot assume that one skill is equal to another. so even though the template for the skill tree may seem well-designed, it allows for a huge error margin due to leaving out class balance in the skill tree. this is not good design by any means.
by contrast a balanced skill tree would recognize that each individual skill of each class is not equal to any other class' skill of the same tier. instead it would seek to regulate the individual classes between each other in order to preserve balance (this is an example of how it could potentially be done, there could be other ways of reaching the same result).