Hunt train reminds me of FATE trains, which reminds me of mindless zerg-ing. Good opportunity to chat, but opportunity, imo, to 'play' the game itself. Pros and cons lol.
I still think it might be good to encourage the 'hunt' part of the aspect while taking down the mass zerg into smaller waves. Concept was something inspired to some Dark Souls mechanics, but basically hunts would when alive be worth more in some fashion (perhaps an extra drop) but they wouldn't scale anymore (except perhaps purposefully designed for chaos world bosses). Then once a hunt is killed the leave behind a mark, which can be interacted with to gain a rough idea of how old the death is, and also to engage the hunt in a phased duel (would create a sphere phase around that area where you'd then fight in that space). I liked the idea of kindling to help purify the spirit or what have you, and how old the death was would determine the maximal scale you could kindle to (but optionally you can always go to lower scales). Each reduction in scale reducing amount rolls, so if there was normally x, y, z drops, a tier down might be x, y or z rolls (meaning you have one less roll and that second roll is shared, step down from that would be x or y or z, instead of two you've only one and it's shared cross all groups). Purpose, besides time, to reduce the tier would be for different group sizes and levels. If you're a solo max rank player fighting an S rank level 50 you might go full power, but if you're two players level 50 you might go to half strength (reducing hp / damage of the hunt). Another concept might be special items you might gather that turn kindling up a notch (kindle the fire demon with a special stone that drops from Ifrit and suddenly you've hunt EX).
Now you can make hunts an activity at pretty much any time of day or situation but also you would gain more from finding the hunt alive, so there is that bonus for players who are into the search. Meanwhile the info of death is relatively public knowledge. Also due to greater accessibility I feel it would be fair to add some crafts or special drops to them without it causing more old school mmo problems. At the same time might as well turn the current hunt log which has been abandoned into a hunt log that relates to hunts, rewards for that as well.
System that encourages active hunters, doesn't greatly punish others, especially preventing issues where some high level murder solos your content that is considered active for you (or from other servers), allows tighter gameplay balance (if you joined a hunt party you'd almost always have up to 8 players fighting mini bosses, rather than 200). Etc.. The reward rate would roughly be what a good day of hunt trains are of as of now (as you could go from hunt to hunt to hunt non-stop, but each battle experience would be more specific to you and your group rather than a giant ball of death, important that the hunts balance is adjusted to that otherwise it would actually be a lot slower lol).
Of course I think world boss experience has it's place, I just don't think normal hunts are anyway where equipped to handle that experience without it being basically "brain off, make as much credit awarding moves as possible as fast as possible, then teleport to the next location you're told to as quickly as possible". (which is basically just reiterating what you said lol).
On world bosses it would be cool to see some greater systems into it- I recall some GW2 systems for some of their zone bosses that were pretty cool. Before we were so popular I had thought it would be neat when a world boss happens there was a staging camp that was built up as more players joined, you could do some pre-fight prep work (including DoH/DoL stuff), and then the area would go into multi-phased fights basically- many big chonkin FATEs. Such that you might have 1,000 yalms away cannons firing shackles into a giant boss which helps those under foot climb up, etc (makes me think of one of the first trailers of ARR when 1.0 was still active, with that HUGE Adamantoise in the background of shroud). System that gives you the opportunity to help out in a number of different ways and purpose gain credit at multiple points too. Rather than maybe a 5 minutes to kill Odin it's like a 45 minute ordeal, with opportunity to get credit a few times for those who need to bounce or cannot complete certain tasks (maybe some tasks are more level friendly than others). Like for Odin he's on a Horse so it would make sense he gallops around the battlefield and obviously wields Gungnir (his spear thing). Might be some group to make the fight much easier is trying to find his spear and damage it like a nail in Ifrit fight, with loads and loads of demons spawning around it. Meanwhile great aether shields that create condensed barriers (reducing Odin's galloping distance, and number of times) need to be constructed and supported. If you didn't keep him settled to an area he might literally jump half way cross the map and 1 shot everyone on the way. Anyone below a certain level, not in combat, perhaps just gets slapped hard for the memory or perhaps is revived by some moogles or something xD (no point in murdering a bunch of level 10s who were in the wrong place at the wrong time lol).