I have noticed the same pattern for a while now and I think it can be attributed to NCSoft continually failing to meet the expectations of it's player base.
The recent server location moved the server to a somewhat central location in NA to a location on the far east increasing the ping of more players than it lowered.
They completely botched the handling of of the Moontide costume issue which while it probably helped to increase the player base initially and increase interest in the game, has since turned a lot of players away with NCSofts retaliation against it's community.
"Events" which players relied on in the past to farm oils for gear progression have become more and more limiting with higher/less interesting (afk events) costs for less rewards.
The only way to effectively farm oils outside of events is content that has been revamped three times now. This is supposed to be "Blade and Soul" not "Bland and rip you Soul out with MSP farm simulator." I am not complaining about revamping old content here and there to bring it to the current gear level like they are doing for Naryu Sanctum and potentially Nightshade Harbor, but continuously keeping one instance a core part of the game when it's already not exactly "fun" is excessive and lazy.
New content has been/largely will be, nothing more but further stat padding. The new "Compound" system, the extra gems on pets, the unity system, it's all just an impossible grind to get players to fork out cash for the easy way out.
They have further pushed players into a corner by reducing rewards from dungeons to fix their past mistakes with overzealous events (looking at the Hunters Refuge event) so there is less and less reason to run dungeons once you have farmed your 100 run achievement or farmed out your gear from the latest dungeon.
Honestly the list can go on and in all fairness no company is capable of pleasing it's entire player base, but there has to be some sort of balance between keeping the players happy and keeping the investors happy, otherwise players leave, dungeon ques become empty, revenues drop, and no one wins.