There are key differences in progression as well, between the games. Linearity vs bubbles can change the culture dramatically, with more area specific preferences occuring in the latter. As well there are the issues with Instancing, spawn timing, dungeon accessability, key requirements, gear dependence, strat dependence, stat dependence etc are all details i am ignorant on to some degree when it comes to other MMOs. It is those details that can shape the desirability of the game, and to whom it is desirable.
A game where progression is open and based on capability attracts definition powerplayers. That is, if you can enter the final dungeon at any point in the game without a key, but only be strong enough to actually fight there once you have farmed the content of the second hardest dungeon, and so on.
If its more about time investment, and not necassarily the power of the creatures one can kill for loot, then a more social, RP style base will develop. That is, If to reach final dungeon you need a key randomly dropped off only NPCs from the second last dungeon, and so on.
But that is only assuming one single variable. Other styles can drastically change the atmosphere. Loot styles effect economies, economies effect farm/camp styles, as do NPC availability, like open timed respawn zones, or instances for just you and your party. Each of these variables can effect the demographic of the playerbase, and conflicting influences can often be to blame for an MMO being very popular, or failing to secure steady sales/subscriptions.
So i guess, to sum it all up, only one who has played through every corner of every game, and able to have enjoyed both the extreme power play and RP styles of play, can be a strong witness to the defining natures of MMORPGs. Man, i just totally managed to oust myself of a coherent point. Dude, did it just taste purple for a second there?
