Recently while reading an article on Slashdot about Massively's article on PvP systems I gained some minor insight. The insight didn't come from the article, but instead from one of the comments near the bottom. Here it is:
The problem in my opinion is that players have the "Diablo" mentality where they want to level every 30 minutes and constantly get new, godly equipment.
The only way that I really see PvP working correctly is to have a system where leveling isn't the goal, but is a factor. For example, after you complete so many dungeons, explore so many places in the world, have more personal experience playing the game rather than "xp points"...then you advance a level. The level's wouldn't increase your hit points, mana point, etc. Rather they would allow for new, more difficult game content to be unlocked and possibly alter enemy AI to be more difficult and loot to be scaled to be suitable for new encounters. Of course, you would also be able to learn new abilities at the new level that wouldn't necessarily raise your power to a huge degree over the previous levels spells but, instead, would increase your utility and efficiency.
The key thing that the new levels would do would be to protect low level opponents from being attacked by much higher level opponents. The game would also have to be much more strategy oriented than current games.
I'm not really sure how relevant the comments are to PvP systems, but it does describe a 'better' core MMORPG system.
I built my blog in a hope that I could eventually nut out 'what makes the perfect MMORPG'. MMO Game Design is still a baby in the world, and it will be at least another 15 years before they work out the formula for the ultimate MMORPG, but it's insight like this that helps to move things along.