Everyone who is talking about ability bloat is right imo, I think for the next expansion something like 4 traits and one new ability at the level cap would be the way to go. However 2 things I would like to see that would definitely add some spice to the game would be

1)Give us something akin to glyphs in WoW. I don't know if they still do it but this system that was in WoW a few years ago allowed players to modify thier abilities in certain ways. For example you'd have a skill like regen and you'd have the option of giving it a lower MP cost, longer duration, or shorten the duration but increase the potency.

2)Even though it would be a balancing nightmare, why not let us cross class (certain) job abilities? I hate how the dev team seems to be moving away from what makes the FF MMOs interesting.