Well, yes each skill tree has an enticing skill at the bottom that you probably want to go for. But now that classes go one of two ways rather than just having two skill trees, its easier to pick one.
You can then hybridize with the skills given to you in your advanced class, along with cards + universal skills.
As for the life class system, originally there was no skill tree, that's not exactly how it works. How it works now is unknown, best to just wait see and be surprised \o/