There are many things that the game did well, but when taken in conjunction caused problems or really only appealed to a small number of people.
Difficulty - You have an amazing combat system but is also one of the more complex, most MMO’s require you to tap a single key to execute your special attack, here you may be executing a combo with 3 additional moves that have to be performed in a specific order along with managing cool downs, resources, shields, positing etc along with the wonder AI which has patrolling NPCs and their own combat moves which can leave you being knocked about and stunned for some of the fight. None of this is an issue in itself, but you then have the mission types and rewards for such. After battling through 100 enemies to collect 30 items (as only some enemies carry them) you get back to the quest giver to get some tin and a ‘there you go boy’ to pick up the next mission to do something similar. The rewards hardly justify the effort and even less so if your having to stand around 10 minutes waiting on a spawn cause someone ninja passed you and steals it. You should be a death dealing Barbarian (or whatever class you are) not and this is more so in the end regions constantly fighting for your life as 3+ 85 mobs is a real pain.
Crafting - I don’t think there is a game out there with a more difficult yet less rewarding crafting system. Seriously the time it takes to gather resources and the possibility of finding the note low or empty coupled with the option to constantly be attacked, needing to craft every piece of gear to go up the next tier (leather grind for the win), needing a tier 3 player city to do the level 80 gear and for what. Some blue gear if you have found enough rare materials. Given the massive investment crafting is, you should be able to produce high end game gear and not only if you go on raids to get it but just by virtue that you have ground out the requisite trade skill resource.
Appearance - This game has done amazingly well in capturing the look and feel of the Hyborian age, but as far as vanity slots went it didn’t really go far enough. It should be possible to change the look of your weapon so when you get that Tier weapon you aren’t stuck using some ugly ■■■ primitive blade if you don’t want or can use that primitive blade if that is your thing. Now I think the new tier 3 vanity sets are amazing as I’ve been able to put my DT in to the Assassin T3 set, its so nice to be in an outfit that doesn’t leave my knees exposed or massive gaps where a sword can cut up my torso or simply bare arms. It seems if you where cloth armour you will protect your entire body but if your in heavy armour leaving arms and legs exposed gives that real protection. That said while I like the Assassin T3 set its far from perfect. Looking at other MMO’s and how much they offer to your choice of looking how you want.
So TLDR: Make the game easier, less grinding and more accessible; Make Crafting more useful given the work put in; Give more options for look.
As to the PvP side of things, it didn’t solely kill the game but it sure as hell did nothing to help the game. You have a long difficult grind before you and then you get ganked on top of that. Sure the gankers may say what fun they had but few people who have battled their way to a quest boss and about to complete one of 100 very similar quests to slowly level will find getting ganked and starting all over again from some rez pad which savor the experience. Hell waiting on the Black One Boss to respawn is painful enough now imagine after waiting on him you get ganked before you can kill him and the gank party kill him so even when you get back you will be waiting on the respawn all over again.