One of the issues I feel FFXIV has is that the early game is... extremely boring. And I'm sure a lot of players can agree, whenever we get a dungeon like Sastasha, Halatali or Tam-Tara Deepcroft.
As a way to remedy this, I suggest giving player's access to most of their skills before level 50, but at a diminished effect. Upon reaching the level where one would originally obtain said actions, you instead gain a trait or, depending on the trait or action, nothing at all.
As an example, I've taken the time to lay out how Paladin might look under this system in the following Google Doc.
While the later levels might be less exciting, given you are getting less actions, and instead getting traits or nothing, I feel it would improve the earlier levels and convince players to stick around for longer, while also overall improving the gameplay of earlier levels. There are also a few little tweaks I've thrown in just as a personal opinion, mostly in how Spirits Within's damage is dealt and Clemency.