While i can see the benefit of going with skill trees, I find myself very much disliking them. I much prefer individual skills. Not only is it more simple, but if gives a wider scope available to all players. Players can choose to specialize in just a few areas, or have skills all over the spectrum to be a rounded off character, even though those skills would overall generally be weaker since they'd be at lower levels than those who went more specialized.
Such as:
Character A choses to only learn skills from earth and Life. They can max out those skills rather fast and be specialized in them.
Character B chooses to have a little of all skills, taking one skill from 8 different elements. They have a wider scope of abilities, but individually, they are all weaker.