cheap Idea to implement - sort of

[Jeeqbit]

the overworld in this game is probably the most boring implementation of an overworld in recent memory

Realistically, they only put a lot of effort into the open world when it's a Field Operation, which contains more of the sort of things you'd expect in open worlds in other games.

Thus maybe your hard quest spawns enemies that are not a joke to defeat, you need to ask for help/party up

I wish weekly B ranks were just actually fun battles.

require you to travel long distances without being able to teleport.

This is another example of what Field Operations have usually done right. Except they changed the design in OC to have an aethernet in all 4 corners so although you have to travel still, it's not an amount that feels tedious like, say, Azys Lla, The Lochs, The Tempest, Garlemald where you can find yourself having to go all the way to the other side of the map without teleportation. The main difference with those is you can fly so it doesn't feel as exciting after completing the MSQ due to the complete lack of obstacles.

Unfortunately, if we wanted the travel to be longer than one side of an FFXIV map to the other, we'd need actually bigger zones, which just isn't how the game is designed. I understand 1.0 was proud of the idea there weren't all these loading screens. They abandoned that concept due to issues with their implementation of it and haven't revisited it despite technology advancements and average PCs being better.

for example, perhaps the end boss you spawn does hit so hard you ACTUALLY need a tank and healer, and has enough hit points a damage dealer would be nice addition.

That's one of the issues with the game in general, across the board. They have torn down the concept of the holy trinity so that a dungeon only needs a tank+3 dps, a healer+3 dps, or 4 dps. So that PvP does not need healers. So that role doesn't matter against anything in the open world except max level Rank A and S hunts.

The reason this is a problem is that the holy trinity is what helped make content replayable in many past MMORPGs. It added additional variables to the battles that make it go differently every time, and going differently every time makes it more fun to replay. The dynamic of relying on eachother is something that can go very differently when the holy trinity is at its best.

Occasionally dungeons have a holy trinity effect if you, say, throw a shield on someone to prevent a raid-wide killing them. But if everyone can do the mechanics, which is often the case, it plays out exactly the same. High-End content is affected more by the holy trinity and involves assigning roles (although, this eroded over the expansions to where Endwalker everyone would often do the same mechanics). But because High-End content has often just taken place in a square/circle, assigning roles in different locations has been a bit limited compared to what you can do in a coil-like arena or an A7-like area. Because mechanics deal 9999999999 to the entire party after 1 mistake, it too reduces the impact of the Holy Trinity - part of the beauty of the Holy Trinity is that the veteran players can help cover for the weak links in their team. You know they're newer to the raids so you can watch over and multi-task to make sure they don't struggle with their role. But that's all irrelevant if it deals 9999999999999 damage.

All that is just as relevant an argument for open world content, or Field Operations. FATEs could work if they were more fun to do, but most of the time it's literally just a telegraphed conal AoE. The FATEs in Field Operations actually have good mechanics compared to most open world FATEs, but they are still easy to solo and the scaling means most people never see the mechanics.

Whatever people want to say about Heavensward, the holy trinity at least felt more useful in dungeons then. Not saying the open world was much different.

make good rewards for them please.

I think the main problem is that not everyone considers the same reward good. For some, glamour may be good, for some mounts, for some power progression, but too much power progression will be attacked as the game being too grindy.

I think once again, making rewards tied to player interaction is the answer - for example, there is a mount that crafters can make. But that mount can only be made with materials that drop from certain world activities. So the crafter goes into the open world and obtains those materials on their battle jobs, but perhaps they sometimes need help to get it. This crafting material could be sold on the market board, but given how everyone sells things for 1gil in this game, the material rewards should probably not be sellable on the market board.

If the mount is also not sellable on the market board, it forces players to find a crafter main and ask them to make it for them. Once again promoting social interaction.

This sort of thing is what SE hasn't designed the game around in the slightest.