Imo there’s two main things:

1. Jobs are horrifically, indefensibly boring at lower levels.

2. The game has become effectively a single player visual novel that is hundreds of hours long.

And these two tie together. Most people play games like this, at least initially, for combat. The first few hours of any game with a deep combat system are always not the most compelling. The issue is that 14’s actual gameplay doesn’t get fun for several dozen hours. And, dungeons/trials aside, there’s hardly any combat at all. So basically people want to play the game to fight stuff, hardly get any chances to early on, notice that it isn’t particularly engaging or dynamic when they do get to fight stuff and get bored to the point that they just give up.

The solution is simple: make jobs more fun at early levels. Jobs get more fun, people will actively seek out more combat (like FATEs which are always up despite the fact nobody does them) and the problem basically solved itself. I promise, you won’t overwhelm players by giving them 10 buttons by level 50.