The general player base needs to improve

[Bourne_Endeavor]

You're hearing only the survivors; a lot of people left over it, and don't really show up when we talk about it. This game actually has some seriously massive turnover.

Because Gordias was not properly balanced. Shifting Living Liquid to the fourth fight allows for an easier boss to precede him, thus better preparing players for the upcoming difficulty. I also specifically highlighted tweaking him a bit for balance sake. Regardless, you're also neglecting to mention 3.1 offered no content whatsoever. I would argue people quit more due to the fact outside of Savage you had the following...

Thordon EX
Void Ark
Diadem
Lord of Verminion

This content drought lasted for eight months. Considering Diadem and LoV were universal flops, it's far more likely people left the game due to the utter lack of content, especially since Savage has always remained somewhat niche.

They aren't a challenge. The only challenge is from roaming mobs, if you get two or more on you. When POTD came out, you didn't really spam aoes and ignore stuff, because you didn't have +99/99 gear that doubled your attack pool, nor did you confine yourself to the easiest floors to grind and ignore the tougher ones. You died then the same way you die at 101+, going too fast for random traps and getting too many adds on you.

That's not hard in any sense that it will teach you to play a class better, it's just now "standing in the fire" ends the run, so to say. And even it can be cheapened a little by the classes you take; get rid of DPS and its much easier, since tanks and healers have much more survivability.

Idk what people want, really. You'd need to make savage-styled content to teach people to be good at savage level play, because you can't learn to be good at a harsh dps check without a harsh dps check. You learn not to fall off platforms in titan or rav by being out the whole fight and dealing with the shame of it.

Ironically, you just described difficulty scaling. PotD got easier as you gained strength until it increased again to compensate. If dungeons followed a similar trend, Leveling would be the initial 1-100 floors that eventually get out-scaled while Expert compensates. Unfortunately, the latter has been rendered so braindead easy you scarcely require a pulse.

Actively punishing players for failing mechanics is teaching them—in the same sense making it devoid of any risk inventives ignoring them entirely. When I can get 2-3 vulnerability stacks as the MT in Kefka normal, why do I care to dodge his mechanics? They clearly aren't going to kill me. Now if after a single stack I took substantially higher damage—perhaps being forced back into tank stance—I'll care a whole lot more to avoid them.

You do not require Savage level content to learn the basics. A difficulty curves to steadily increase the challenge at a reasoned pace and can be seen utilized in numerous games. For example sake, let's grab Seymour from FFX. He becomes increasingly more challenging with each encounter assuming you don't overlevel, yet at no point is he ever unbeatable. DPS checks aren't what you need to learn going into Savage, especially as they aren't "harsh" by any standards. You need to learn mechanics and how to properly perform your job—all of which can be readily taught as early as dungeons. Alas, FFXIV refuses to relay any information towards the player and instead hopes better players just pick up the slack.