It's a long shot but I hope this message get pass onto the development team.
Contents like Diadem are now dead with 'no access' into it outside of using an FC ship and even if that is the case you would still need to find enough people to help with the NM in there. Isn't it way past time to nerf it and let us solo it already?
This same trend continued with all the new contents you've made, you simply shift the player population to the new content and forget the old one. Why didn't you enrich old areas, enhance open world gameplay, etc.
How long before Eureka Anemos is virtually impossible to do and you would forget about it like the previouse contents. You also tied achievement to it that make it aggravating for achievement hunter type players where they are willing to put in the time but there are no more people wanting to do the contents.PvP is also another contents that have specific achievement that are impossible to get now due to how little interest in many of the old areas are.
Having invested a lot of time into this game made it very hard for me to just drop it and leave but if this is the direction you are adamant on doing, ie: keep churning new shortlive contents and forget the old ones then at least I can leave this game in peace knowing that I've tried to talk to you(Dev team).
You do remember one of your mantra right? You said " If it isn't fun, you're doing it wrong". If the content that you made is indeed fun then you will have players keep playing it even if the said content offer no reward. Yes such games do exist and I have played them.