I really do enjoy hunting these, but as time goes on and players get stronger and stronger, they're going to die faster and faster.
They've already reached the point where ARR and HW S ranks are basically tomestone/seal pinatas because of how trivial most of them are to even a four player party, and it's not unheard of for ARR S ranks to get picked off by solo players who stumble across them.
The thing is, as long as they drop the currencies they do they'll always be considered "relevant" content going into the future, and so I feel like it's fair that they get some changes to breathe some new life into them, as they were somewhat challenging fights back when they were first released and overall a fun activity for a server's community to take part in.
Having level sync on them and converting them into hidden FATEs like Odin/Coeurlregina would ensure they're able to live for a decent enough amount of time to actually perform some of their mechanics and allow more time for interested players to show up and contribute.
They could even add some new rewards to them like minions or mounts to encourage more people to get involved with spawning them.