I would sum it up, but it deserves more thoughts.
- Issue of balance between factions in PVP. Damn hard to find a good solution IMO. More factions would be cool. More features for squad/platoon. Maybe huge individual bonus if you are fighting outnumbered and malus if you are outnumbering. (let's say your personnal score is divided/multiplied, and the loot have bigger/lower deterioration depending on the balance between teams, for instance). Ultimately, features that encourages faction to spread up and not swarm, while not forbidding it. (It could be quite frustrating if you want to PVP with your friend and the map is forbidden because there are too much of them). On the other hand, it is better to have multiple small scale PVP at the same time than a singe swarm vs swarm big battle. I can totally relate to Seki comment. At some point Lawyers (Judges/TTTLA/BBS) were dominating the server, starving for PVP, only having it when V-TEC were enough to swarm us. On the other hand Family/BBoys rarelly tried anything and were swarmed by us when they did. A typical day was doing assignement, fighting blues, doing assignement, fighting blues... Got tiresome after a while.... Even if we lose far too much currently, i prefer that as it means more challenge. Which would be good for everyone is a good balance of lose/win.
- The newbies were lost. The server attracted too many players that were new to any kind of Fonline. They got the news from Kotaku, PC Gamer and other websites not linked to Fonline. These guys were lost and crippled, even while the server was casual friendly. There are also others that didn't understand english. (i don't know if localization could happen any day, considering the original version is a big long WIP. We are many people willing to translate if we have the files). Some were lucky or dared to ask, but many were just there, not knowing what to do. On the other hand, the Fonline "veterans" were still fresh in AOP, building their strenghts and enjoying the features. They didn't have much time to ask every single noob they saw if they had problems or if they could need help for assignements/scavenging/other mechanics. Now, everyone is used to the features and can take some time to teach the noobs. But considering the population is already low, the veterans aren't always connected to teach those noobs. Without fresh blood, the population can only go down.
- Fonline 2's wipe, Wasteland 2 release, Dragonfall Director's Cut, Dead State etc... There are so many isometric games released these. You have greaters choices compared with the early days of Fonline (which appeared during a dark period for isometric games). It could be hard to some people to stay focused in a game with no story/plots/evolutions, while there are so many other games/universes that wait for you to explore.
- There isn't much reasons to stay in town. You basically go in to scavenge, then go out (if you were lucky and didn't attract death squad when starting timer), go to take a zone and/or do PVP, then go out). There is currently not enough reason to just stay in, idle, patroll, look for adventure. There is almost no noob to protect, no quest to do in town, no special encounters, no rare stuff that surprise you, no interaction with NPC beside fight them and watch them walk. There should be traders, NPC civilian that you could protect, special boss that appear randomly and attack people. The zones in the center of the city should be harder, with stronger NPC than the peripheric zones. Currently, i don't see much reasons to stay in the city.
- One example of the many things that could be done. In FO2238, at some point, several factions were associated to create a faction, the WWP, that would protect Redding from PK. The simple fact of holding the city was a challenge on itself, that occupied the PVP player for large scale batte, but also leaders for diplomacy. But when there wasn't PVP battle, people had an occupation. They had to keep a presence in town, so the strangers/weakers players could trade in town, with npc or other players. There was also a mine with critters that we had to kill, so the miners weren't hurt. Fighters could do protection duty, while the others could improve their way of life by trading/mining with more safety. As a consequences, many more players were coming to mine and trade. On the other hand, some nasty players were also interested in coming to sneakingly murder some of these people coming back from trade/mining, the pocket full of goodies. These murderers/outlaws attracted more patrollers to defend the civilians. As there was unique ressources there, players had to come in. As there was danger, other players came to defend them. As there were other players defending it, it created a set of new interractions. If some areas were too hard for loners/newbies but had more interesting ressources, it could motivate some defenders to bring the newbies with them, to fend off those nasty critters, and motivate some nasty players to ambush them on the way back. Currently, the only nasty critters that i can find are in the dungeons, that are self contained and don't promote player interactions.
- If there isn't much to do in town, there is too much to do outside town. You can trade/mine/do assignements/do dungeons/gather Power armor parts outside the phoenix open map. For most of these stuff, you are even forced to be outside Phoenix. Which means that, in order to do many necessary stuff, you are forced to avoid interractions with players from other factions or other players at all if you do those only with your buddies. That lack of interraction is likely to make some of the other players leave, especially loners and small groups.
- The game changing updates were slow paced. The two dungeons appeared late and far between. The diplomacy features, the Phoenix inhabitants, the cars, things that were announced early on are yet to be seen. On the other hand, they were many changelog about minor things like weapons or bleeding. I am not saying the dev are at fault, considering the huge work they have done so far, but i heard some complains about "What the hell ? The server lack X or Z feature and they add ANOTHER gun !" Although i can't confirm if any of them left because of this. Hell, i still complain about the sneak/Melee still being OP after 3 months, but i don't know anyone who left because of this.
- The Power armor and the grinding it involves, plus the fact the outnumbered teams didn't want to lose them, and were even more underpowered. The server need balance, not the strong becoming stronger and the weak becoming weaker. Fortunaly, most teams don't use it any more, but when the PA changelog appeared, the players had no way to know how it would end up. For those who already left, it is too late to see that those PA weren't much used. They are simply gone.
- I don't want to fault the dev about that, since their bring us that wonderfull rethink of the whole Fonline philosophy, but i get the impression most the team went silent or inactive. It was more engaging when you knew where people were heading, or when there was more human strenght to put at work. I hope this is temporary and Shangalar/Lidae/Rynn and others will come back some day and bring some juice into the machine.
- The low player base on itself, is something that speed up that decrease. If you have no one or not much people to interact with when you login, you are likely to logoff quickly. Then the guy that connect afterward won't see you or others and log-off too. And so on...