The upside of this game's design is that all the jobs are incredibly balanced, and we don't have jobs that are shunned by the community or excluded from certain content types like we saw in XI.
This "balance above all" is actually killing game. All classes play the same. Nothinbg is unique. Zero theorycrafting. Why not make everything equally unequal? For example, trial A is best for blms, trial B is best for drgs and etc The game would get so much more depth in instant.
In XIV, I could leave the game for six months, come back and have a high enough iLevel to succeed in most content within a month or two.
And that's exactly the problem we are all talking about.

Actually those 2 things combined are the root reason of all problems.

It's either throw away any sights of balance, but keep gear raining with no effort, so everyone can play any job and have fun.

OR

Keep everything balanced, but gear hard to obtain and last 1-2 years/

But not both. Any of those ways will fix game for the most part.