What the game needs, in order of importance:
1. Better server + net coding. A laggy MMO is a dead MMO. *coughDefiancecough* The server needs to be reliable with proper coding. I have no problem with new server and everything, it's 2018. Can't keep using outdated hardware/software if one wants to remain relevant.
2. The game needs to be rewarding to be fun. The reason the game always struggled to retain new players pre-Gore is that most leave the game in sector 2-3. They never make it beyond that to reach lvl55 (unless they skip 90% of the content and power-level to lvl55, which I personally find a guaranteed quick way to get bored of any game). People leave that early because in those sectors it becomes very clear how awful the effort : reward ratio is. Why bother doing anything if you get peanuts in return for an arduous 30min Master boss fight? G1 mentioned at least 3 times they would fix the reward table, welp that never happened. I've personally seen people ragequit the game after getting terrible rewards from quests for the umpteenth time. Multiplying the quests' chip reward by 10 would've go a loooong way in making quests worthwhile. Also, that nonsense of item rewards 10 levels lower than the quest level itself... seriously what is wrong with the person who thought that was a good thing?
3. The character stat building system is..... not good. It never really was. The game claims to champion freedom of choice, you can define yourself. (one of the game's main selling point that attracts new people). But the character system is so inflexible and convoluted you pretty much always had to build specific meta builds. It should've just chosen the generic class system with fixed skill tree like any generic MMO instead. People coming in here with an idea in mind how to build their character end up realizing later they can't do it due to the extreme limitations and don't want to make a gimp build, So follow the meta or go away. Unsurprisingly, many choose the latter.
4. Capitalize on the fact that this game is huge. 1000+ square kilometers....yet more than half of it goes to waste. There is so much enormous empty spaces everywhere. They're filled with generic enemies and common nodes. There is no reason to ever enter these vast wastelands. Would've helped if at random some rare resources (or enemies that drop these resources) would spawn in these places, this would promote exploring. But noooooooo, let's put all the rare stuff inside pvp zones. That oughta show those pve players how much we appreciate them! G1 did an amazing job driving the PVE player base away with terrible decisions after terrible decisions. GORE, broken Outpost and Dome instantly killed off 4 pve clans I was in. They made exploration and crafting on such a huge area a zero-purpose goal. Veteran players were actively telling new players to just go to power-level locations to reach lvl55 as quickly as possible and then grind their sanity away in Citadel/Dome for tokens. Tokens!!!
5. Make AI combat worthwhile. Combat against npc is just a matter of outlasting them while standing still. There is no strategy involved at all. Would be nice if their accuracy would lower when you move around a lot. Cause right now everything just aimbots you, why bother moving? Because of this, combat can be done with one hand. And this lacking combat system gets mentioned a lot in reviews as a biiiiig negative.
6. All recipes need to be relevant. The amount of recipes in this game is amazing. Too bad that for its majority it's all a giant waste of time and space. We have no reason to craft most of this stuff when it's pretty obvious what the best thing of each category is.
7. Crafting queue needs to be increased. This whole 1 queue for f2p and 3 queues for freemium is brutal. Other f2p games offer more for less. New players need to feel invited to spend money, not driven away right from the beginning as a punishment for not spending cash. The target audience of 2018 is not the same as 10 years ago. Still using the rules from way back then will never make you competitive.
100. Re-skin everything to make them look more shiny and modern. Yeah, that won't help whatsoever until the above is addressed first.
Realistically speaking, can all the above be done cheaper than just making a new game from scratch? As it stands, FE is so broken and neglected with rushed/unfinished poorly planned content..... how do/can you fix that without throwing the baby away with the bathwater?
That is THE point of playing PVE. One does not power-level and THEN go do those things. You do all those things and you automatically level up in the meantime. The road to lvl 55 needs to be fun and engaging, reaching endlevel is not the one and only reason people play MMOs. To many, the journey matters more than the goal. If the journey is awful, who will care about the goal? They just leave for other games instead.
"A lot". I'm not buying that at all. When somebody says "I am a PVE player", that means they do not and never will be interested in fighting other players. They will go out of their way to avoid PVP. a pve player will never be a pvp player. A pvp player can like both pvp and pve however. When the game clearly became anti-pve after GORE, the pve player base left in a massive exodus. There was nothing left for them to do and the little they had became irrelevant due to power creep and depressingly boring token-grinding content.