No necessarily "trees" but purchasing Guild Mark abilities that move towards an advanced job.

If they remove Phys Lv and a few other things, characters will be too "cookie-cutter". We all want character builds, and removing that element is MMO suicide. Part of "builds" are focusing on certain abilities that suit your fighting style, gear and stats. Akin to feats in D&D, they would be limited in number and improve a WS beyond the "stock" ability.

All you need are ranks to get WS now, this would flesh out characters some... I know they are attempting to do that with other job's skills .... but that does nothing for the feel of your main job per se.