The general player base needs to improve

[RiyahArp]

This is false. People get better by gradual increments in difficulty, not massive leaps. You may prefer that method personally but I can guarantee you never learned something hard by just throwing yourself at the most difficult part and overcoming it.

No, people generally don't improve that way, or desire to make improvements. People naturally coast on their level of skill unless forced by something beyond it to finally change, be it a hard college class or what. You can argue after they have different learning styles, but this game really just has one, repeat the dumb thing until you mastered it.

As for percentage increases, most people wouldn't notice a 1-2% variation or even 10%. You also have more of a balanced difficulty spike; hard content is hard because they pile on everything at once i think.

[Bourne_Endeavor]

No, people generally don't improve that way, or desire to make improvements. People naturally coast on their level of skill unless forced by something beyond it to finally change, be it a hard college class or what. You can argue after they have different learning styles, but this game really just has one, repeat the dumb thing until you mastered it.
As for percentage increases, most people wouldn't notice a 1-2% variation or even 10%. You also have more of a balanced difficulty spike; hard content is hard because they pile on everything at once i think.

Psychology studies argue otherwise. If people perceive something nigh impossible from the onset, they are significantly less inclined to bother; the "I can't possibly do this, so why even try?" effect. Conversely, gradual increments fuel endorphins due to people seeing actual results, even if only slight. Provided they remained engage, people will absolutely notice 5-10%. They may even notice just 1-2% with high enough adrenaline. This is why gradual difficulty curves are used in all forms of activity not just video games. You wouldn't expose someone to advance computer science without starting from the basics. In the same sense, fights in FFXIV shouldn't follow a pattern of: "Easy -> Easy-ish -> Hard -> Very hard -> OMFG"

Better even. Let's look at the Primals since they're more "Casual" content.

Susano -> Easy
Lakshmi - Very easy
Shinryu - Hard
Byakko - Easy

Difficulty assessment is relative only to each respective primal not overall content

The problem isn't Shinryu's difficulty per se, but the sudden leap with little to no preparation. Unfortunately, this inconsistent scaling can be seen across multiple tiers of content. While not the sole contributor to people's lackluster skill, it does play a noteworthy factor.