PvP (Player vs. Player) is a draw to many players and could be a draw to nearly everyone if implemented correctly.
But there are varied problems which make it fail. These problems span from MMO to MMO and can incorporated into the following terms:
Ganking: Many players hate ganking. Ganking occurs when you come into a zone, instance, or area and are immediately killed. It is almost as if you were barely able to open your eyes before you die. This occurs most often on FFA ("Free For All") servers. Because of ganking, many players will stay away from FFA. Others adapt by stripping down or by surrounding themselves with friends. Sometimes the fun in this is trying to figure out how to kill the gankers.
Graverobbing: This occurs less and less. In some games, when you die, your items because "treasure" and lootable by others. The industry has been trending against graverobbing because it causes their subscriber numbers to decrease. Basically, people won't play if they lose their l33t gear.
GraveCamping: Also known by other terms, this occurs when your opponent waits at your gravesite or respawning point. When you get resurrected or raised, they kill you again.
FoTM: Flavor of the Month builds represent a problem in the aspect of patches and upgrades. Today's "Warrior" may be the ultimate killing build. He can hack and slash and mow down his opponents before he falls. But what happens after patch 2.0? Well, now the "Sorcerer" has his spells upgraded. They completely overwhelm the warrior now. So basically, what you have is people moving from build to build to build. This usually removes people who enjoy Roleplaying from the RP equation. They prefer a more even playing field.
Exploits: An exploit is a technique or tool of some sort that operates in a manner that completely unbalances the game towards the favor of the exploiter. In PvP terms, exploiting basically makes skill pointless. This is a bane.
Obviously, there can be more problems attributed in a poorly made PvP MMO...
So what are the solutions?
Basically, PvP is being streamlined at this time. In other words, we think of it only in terms of fighting. Why is this so bad? Simple. Fighting is what fighters do. Thieves steal, Assassin's murder, Wizards cast spells, Clerics pray, Druids plant trees and so on... So, the problem you run into is that every class has to learn to fight to PvP.
Perhaps you've been trained to think this is necessary, but it is not. I assure you that a Diplomat class could be just as effective a PvPer than a Barbarian. Let's take this scenario, and I will show you an example.
Example 1: Barbarian vs. Diplomat
Rogg the barbarian has learned Ionysus the Diplomat has insulted his clan. Therefore, Ionysus must die. Hiding in the alleys, Rogg waits for Ionysus to pass by...this should be a simple murder by chopping off his head. No diplomat can stand against the mighty barbarian!
But Ionysus never appears.
Hidden in his chambers, the diplomat Ionysus speaks with his runners, learning of the barbarian's advances. When Rogg charged into the city, he was notified. When Rogg hid in the alleyways, he was forewarned. Clearly the barbarian is a fool if he believes a diplomat will try to match him in swords.
Having enough, Ionysus hails the captain of the guards and tells him to have Rogg picked up for "public disturbances". Hopefully the captain will have no problems and throw the barbarian in stocks. Once the trial begins...well, a judge can easily be bribed to execute an uncivilized beast...
Perhaps you've been trained to think invisibility and stealth are the key elements to PvP. Once again, I assure you that a mage can be as effective as an assassin or thief.
Example 2: Thief vs. Mage
Sliver the Thief, cutthroat master, has decided to put some of his poisons and blades in the back of WolfMane the Wizard. WolfMane has been known to carry lots of cash as well as magical trinkets. This could be Sliver's big score in the guild. Remaining silent, Sliver carefully adheres to the shadows. His presence is undected. WolfMane is merely steps away and the night will cloak his attack.
Unsliding his envenomed dagger, Sliver prepares to strike right between the shoulder blades. He leaps...but then falls short. Something continues to pull his muscles to the ground...
"A nice defensive spell...Gravity Field," mutters WolfMane, "I can't attack you, of course, but you clearly did not know that. There is a way to circumvent the magic, but I doubt that matters now, eh?"
Weaving his hands in a complex manner, a strange figure emerges from the ground...a figure composed of rock and mud. WolfMane had summoned an elemental.
"As I said, I cannot attack you, poor street urchin...but my friend here should be able to..."
Sliver gasped for breath. His muscles groaned as he tried to lift himself off the ground. If he could just reach the mage, his poison would kill him in seconds. His desperate struggles met futility as his skull collapsed under the weight of stone...
Having provided some examples, I would like to point out what truly makes PvP exciting.
Strengths but weaknesses. Its fine to have ultimate attacks and defenses, but each should have a way to be beaten. A strong defense should have equally taxing features. A superior attack, should have a way to be beaten. This level of balance means that the situation and opponent dictates what works best...not the same attack or defense...over and over.
Anonymity. By hiding things such as levels, statistics, classes, and active effects, you are nullifying knowledge. Remember that knowledge is power. So, when you attack the person in the mage's robes, is he truly a mage? Or is he a thief in disguise? Because if he isn't a mage, your magic-nullifying attack will be pointless. As well, people are more careful when attacking an unknown. You're more inclined to have backup plans, associates, etc., in case you are wrong.
Relative Advantages: What makes a city so important? The relative safety it provides...known as "laws". Obviously, thieves, diplomats and other classes can bend laws from time to time, but the concept remains. Your character should have a place he or she can go that gives him/her the edge. For example, Druids and Rangers (barbarians, I suppose) would certainly reign supreme in the forest settings. Thieves, Diplomats, and law-abiders in the city. Paladins, Mercs, and Fighters would thrive on a battlefield or in a duel. The key element is your character being able to walk or set him/herself up in environmental conditions that give him the edge.
Community: This might be a suprise to other PvPers, but the community is important. If you know who "Rogg the barbarian" is, perhaps you'll stay clear of him. Likewise, if a "new face" appears in the area, you may study him or her until you know more. Likewise, players of a community tend to stand together when a newcomer arrives and tries to hack n slash his way through the natives. Communities thrive because they are communities.
Allow Retainment Measures. While item stealing should be allowed, it should also be circumventable. In other words, things like soul-bonding or something should be possible. These types of measures help the economy as well. By soul-bonding, I am not referring to the WOW version. This form of bonding is a magical countermeasure that allows you to call upon your item, or have it return to a place of your keeping if you should lose it. Player Houses, vaults and storage places off the body also help.
I'm also interested in any suggestions and willing to debate :)