From what Im gathering from the same 5 people who make up 95+% of the forum posts, there are two linked issues. Lack of PvP driven in part by lack of dungeon farming because gold is so abundant and cheap to buy for cash.
How can I break this down for tards to understand... PVP IS NOT PVM. PVP SHOULDN'T BE IN DUNGEONS. THAT IS PKING! Most people PvMing DO NOT WANT TO PVP, and if you force them to pvp by attacking them while they are trying to farm, and are not good enough to kill the pvper, THEY QUIT! Its quite simple. Or they are forced to join a nutcup group to defend their interests (good luck).
Imagine for a second this game is life. In life, there is a wide spectrum of people. There are babies, there are women, there are elderly, there are obese, etc. A wide spectrum of people. Now, imagine a 6'2" 220 lbs man, killing a 3 month old 10 lbs baby. Was this a fair match up? What would society say? They would probably be outraged right? They would probably call for capital punishment right? Is the man tough, or cool for killing the baby? NO! How about if the man kills any other helpless person unprovoked? What would societies reaction be? The Punishment demanded would be severe. Now for this analogy, replace man with PvPer, replace baby with newbie, and replace women, elderly, obese, with rare collector, PvMer, idoc'er etc. In life there is a huge cross section of lifestyles with people of different ages, shapes, and sizes, and if it was open season to kill all these people in life (mmo sandbox) it would be anarchy. And people hiding on rooftops with shotguns with no reason for women, children or elderly to be alive. Thankfully, there are LAWS in life that make criminals reconsider mass murder. There should also be laws in game making criminals reconsider mass murder. Men can join gangs (order / chaos) to fight other men, or be a sports fan defending local team (factions). Or a drunken bar fight (someone goes grey). Or even be a criminal looking for someone to pick fight with (red waiting for someone to attack).
So what ends up happening? Well the defenseless quit / join a zerg and the server is polarized into PvP areas or safe zones. To bring numbers back there needs to be more restrains keeping sociopaths from killing women and children. The reason your "PvP" areas get smaller and smaller is because these areas should not be PvP areas. Man up and fight PvPers, not women and children. Let them be, or face some sort of REAL consequence. Being a murderer has virtually no repercussions.
*LACK OF GOLD FARMING*
This issue is easier to notice and simpler to solve. The server has been running for 10 years. In that time players have earned lots of gold through farming and corrupt staff who added have added an unknown amount of checks into the market. The solutions to get players back out with a reason to farm in dungeons again are:
*SERVER WIPE (My first choice)
*More severe gold syncs like Xmas gifts (marginally help)
*reduce drop amounts on mobs
*CUB rewards for checks
*STAFF THAT DON'T CREATE GOLD