For example, if I am starting a new Primalist, and I am deciding between beastmaster or shaman, it would be great if I could see skill trees for things like avalanche, tornado, summon bears etc, without having to level all the way up and unlock them (or look on a wiki).
Perhaps use the bottom half of the Skills & Specializations tab to show the locked skills and allow you to view the trees. Either that or allow us to click on the skill in the Passives tree to bring up the skill tree window for that skill.