the problem is some people wanted class uniqueness, SE interpreted this as rigid roles for each class, and no one else being able to do whatever some one was good at, so they made glad the best tank by nerfing marauder and pugilist tools, and stamina change, they made conjurer into a healing class, and gave them the best heals, and they let archer remain the safest and highest dps in a party.

they should have tweaked initial gameplay mechanics, added a job/role system that pulls from your available class skills to be a specialized role.
IE whm is a caster that focus on healing and protection, and pulls various skills from multiple jobs to achieve this. not con is the bootleg whm of whom, half his skills are useless because he needs all his mp to cure. then later he can fully abandon his other skills and become a pure mage, and the elemental skills can be left in the dirt.

even if thaum tries to cross class them they wont be worth it, thaum best split thier elemental strength among 3 elements to maximize either light or dark dmg, whereas con needs to specialize into 1 or 2 elements. and on top of that, just cross classing the skill will drop its damage with the same mattack to to prolly around 65-75% of whatever the con damage would have been on that spell.

So unless they choose to go back on their plans and make con into a blm and a whm, that means elemental magic is just fireworks for conjurers who will have to wear the chains of a healer for the next 6 months to a year.

btw, jobs arent expected to be in till after 1.20 at earliest, all they said is they would have formulated thier plan by the end of 1.20, not have it implemented