Suggestion for Stat Changes

So we have strength, dexterity, vitality, intelligence, mind, and piety.

I think there should be encouragement for classes/jobs to pursue development in other areas.

Every 75 or 100 points of strength should increase inventory holding space by one, and improve chance of critical hit. Every 100 Dex points should increase evasion by .5% or some such thing, as well as increase accuracy. Every 50 vitality points should give a .5% chance you will have a critical guard, in which you take half damage or even 3/4ths damage. Every 100 intelligence points should give a 1% chance any technique or skill will deal strong elemental damage, essentially a magical critical hit regardless of class. Every 100 mind increases HP regeneration rate by 1%. Every 100 piety should reduce TP and MP costs by 1%. I think little things like that will make a huge but totally balanced difference, plus it'll encourage players to be different.

I think there a big issues with this idea. First off, each job's armour doesn't have the primary stats of the other jobs so how would they get said stats?

That aside, say there were easy ways to get the other stats.
Currently high end melee jobs have 500 strength, so they get 5 extra bag spaces? Sure that sounds nice but I doubt any other job would go for it, since it takes away from their primary damage/healing source.
Every 100 Dex gain evasion? It already increases parry and block rate (for plds). If it increases accuracy what's the point of the accuracy stat? Why would bards get a free pass on getting more accuracy innately then other jobs?
Every 100 Intelligence gain 1% chance to do more damage? Why not just increase your main stat to constantly do more damage, this would end up only buffing Blm and smn damage outside of their jobs main abilities.
Hp Regen is already really low in combat, increasing it by 1% using mind would be nothing to write home about. Nor would anyway care for it.
The piety one is the most pointless out of the ones you suggested. If you're main stat is higher, you do more damage, thus you'd need to use less tp or mp in the long run since the encounter ends earlier. So why would you gimp yourself to get more piety? Considering for TP based jobs it would do NOTHING else. Even for BLM and SMN they have ways to get around their mp pools. For healers they have enough piety for any given encounter if they are the right gear level, for tanks if they really need tp army's paeon is still a thing.

These suggestions wouldn't encourage players to be different at all, it would just give jobs that have the right primary stats a small buff. This isn't balanced at all as you state.

Well I'm suggesting something similar, those are just examples, and I'm also thinking in the long run.