I definitely agree with the view of the OP and several others in the thread that the addition of more job traits could really help to flesh out job customization. The obvious way to implement such traits would be to have each class provide the basic stat boosts for the things it normally excels at.

However, I think that there's a good way to really expand upon this. Combining traits should offer additional bonus, and those bonuses might even be affected by your current class.

Here's my example. Say you throw on a couple of attack boost and magic potency traits. If you're a gladiator, this combination could provide an added strength bonus to your elemental weapon skills. If you're a lancer, marauder, or archer you might be provided with an additional boost to damaging spells you cast. Conjurer and Thaumaturge might be gifted with a strong bonus to any of their tp based skills.

Now of course, my example was just off the top of my head, so I'm sure there could be a better way to implement the specifics. Still, I think that the idea of bonuses from trait combinations would be a nice way to reward creative customization from players.