Suggestion : Give each job two distincts "purpose" to build on future customization

[Reynhart]

There are currently three classes that would clearly benefit from giving them two distinct roles

Just to be clear, this is not about severals "roles" but different spec. They already said that they're not fond of the idea of multiple roles (Which is really sad, in my opinion)
SMN would still be a pure DPS, but maybe you can have either traits to enhance your DoTs for more sustained and AoE damage, of traits to enhance your pet and your direct damaging spells, for more burst damage

Paladin isn't suited to DPS

It isn't suited for DPS...as it is. If you had trait to enhance the job, it could very well be. Like I said above, if you want to max your DPS, you want to avoid using RoH as much as you can. But, when you're MT, not using it means building less enmity. If you had a trait to give an Enmity boost to RA, it would solve the problem. But as an OT, you clearly wouldn't want enmity, so you'd probably chose another trait.

This could create two templates for PLD, one that focuses on MT with higher enmity, better block rate, etc...and the other on OT, with higher DPS or support skills.
What is interesting is that you could still keep the same meta, where everything focuses on more DPS even when designing traits for tanks. The higher enmity gain for more RA combo, a better block for more frequent Shield Swipe proc, etc...

I haven't played Ninja, but what I know about MNK is that it's a really good sustained DPS, but with less burst damage. Maybe you could add traits to push it in that direction.