So, the only REAL customization comes from hero (character) abilities. But you have to ask yourself, why do they seem so chill and laissez faire about balance issues? Ill tell you why - because the character skills, within their various types, are going to be almost totally homogeneous. Sure, a wizard will have a blink ability to keep it mobile, but it will be almost identical to the warrior's leap, and the ranger's ground slide or whatever. Who cares which one you pick? They are basically the same skill with different animations...
Prove me wrong Sony.