I play TONS of MMORPGs , and here are my opinions on what can make a good MMORPG:
Job Changes:
Say for a fact that you have 3 main classes: Mages,Archers,Knights. Upon leveling up to a standard level say… 25 they can begin a quest in order to rank up in their profession (i.e Archers would rank up to Rangers, Mages in to sorcerers and knights into Warlords or something of the sort). In many of the games I play, they don’t only have one job change, but multiple. And the ones at a higher level tend to branch out kind of like how World//Zero did theirs in the way that Mages can either become attack mages or healing mages. You could have archers turn into rangers then at level 50 or something they have the choice if they want to become Hunters or long-shots. This is a huge thing for me in most MMORPGs because when you rank up, you tend to get cooler and stronger abilities which keeps players playing.
Quests:
Add quests! these will help enhance players levels along with give them money to use for enhancing weapons or buying new items. Quests are important to push along the story of the game which brings me along to my next point -
Plot:
Have a darn good plot to follow! One of the MMORPGs I play has a plot where you wake up from what seems like a coma only to find out you fought in a great war. And since you just woke up, your power level is low, and since you cant remember much, you can only use basic spells/combat moves. Along the way, you do story-line quests in order to get to job changes and learn more about your past, along with little side quests just to help random NPCs out. I really think plot is important, and if done right, it can lead to an amazing game. I also suggest adding small cutscenes for each quest.
Linearity:
I would have the maps form a linear path ( hypothetically speaking ) where you start in the smallest town with the easiest mobs and as you travel, the mobs gradually get harder. In some games I play, they even have a cross-roads at some point in the map with a town you need to go to for a quest but alternately leading to the same villages down the road. I suggest not making the maps too complex and easy to traverse, something like Vesteria always got me confused because I really don’t know where I’m going and if I took a small hiatus, I would be utterly lost.
Indicators:
Show where the character needs to go! This is another thing in Vesteria that I really don’t like. When I became the level to turn into a class of my choice, I had no idea who to talk to, or where to go for that matter in order to find the NPCs. Give the player lots of notice and help so they know exactly what to do and/or travel.
Balancing:
This is a tough one! You have to find the right combination of “Not too hard, but not too easy”. If your game is too easy, players will reach the max level that you set within a couple days then quit due to boredom. If your game is too hard, players will quit before they even give the game a chance! You need to find the middle man in this situation where at first its pretty easy to level up, but later on you need to do a bunch of quests to get levels. It’s understandable if you are level say… 75 and maybe you get 0.5% exp per mob you kill, it just means that the game is getting harder but if I was level 10 and a mob I killed gave me only 1%, i would have to kill 100 mobs just to level up to get to level 11 ( not including quests). If you include quests, you need to find the balance between how much each mob gives in terms of experience and how much exp each quests gives. A lot of MMORPGs I play make it so you get a small to decent amount of experience depending on which mob you kill, and a hefty amount for quests to urge players to do more quests instead of grinding.
Drops/Bosses:
Bosses are HUGE in MMORPGs!!! They fact that a player can grind a boss over and over again to get a legendary drop is basically what makes an MMORPG! Say there’s an orc base (instance dungeon), and each mob in the dungeon is 2x stronger than each mob outside of the dungeon. If a player battles through the dungeon and reaches a boss and attempts to kill it, its indescribably satisfying once you kill it and see you won a legendary item like wings are super rare armour that you can flaunt around towns to other people with. I wouldn’t say that the way that Adventure Up does their dungeons is the way to go, because it seems that it’s kind of annoying having to be teleported every single time you beat it and every single time you want to join the dungeon. I would suggest (and this is my opinion) do have one teleport that leads to an Open-World dungeon with plenty of mobs for everyone, and have 3-4 boss rooms in the dungeon so everyone gets a chance at the bosses. This way, players can stay as long as they want in the dungeon and farm bosses, and you can adjust drop rates accordingly.
I seemed to have rambled on quite a bit but these are the facts that I think make a good MMORPG! Hope you get a chance to read through most of it 