What if we got the Sub-Job System in FFXIV?

[Delmontyb]

With the fact that the cross-role skills are going to give us all 10... why not with 5.0 shift the system to something tried and true within the Final Fantasy universe?

I get that there would be adjustments, and I also don't agree that the cross-class system is like the sub job system.

It's a lot to ask, but I'd love to know your thoughts? I think there will easily be a "preferred" sub job for each job or role... But we have that now with cross-role, etc... Having been playing Octopath Traveler, I just love the sub job system...

[Updated with more context 8/13/2018]
I ended up making a video about this topic if anyone is interested, summarizing the thought, what is Sub Jobs in FFXIV's case where just a way to add passive buffs to your abilities, not change or introduce new abilities.

For example:

Protect, based off your sub job it could do the following:
1. Give the player extra damage resistance or
2. Give the player a healing over time effect or
3. Give the player an MP refresh over time effect

Limit players sub job option to one of three options to give it a rock/paper/scissors type of balance going forward.

Another example was ensuna:
1. Allow ensuna to heal for a little bit as well as remove a debuff or
2. Ensuna is now an AOE or
3. Ensuna removes more than one debuff or
4. Ensuna removes and prevents the next debuff

Here is the video if interested

Thoughts?