Each of these "holy trinity" roles is based on one of the basic functional classes of the original Dungeons & Dragons: fighter, mage, and cleric (healer) respectively. But we've forgotten that all of these roles were distilled from archetypes in fantasy fiction and heroic myths... and those archetypes were used to dramatize real differences between how people see the world.
So I'd like to take a look back at D&D to show how its classes, on which the roles and classes of most modern MMORPGs are based, are actually derived from mythical archetypes which recognize that people have distinctively different worldviews. And I'll then show how that understanding of gameplay roles as archetypes points the way toward designing better gameplay around those roles.
Back to the Past
The effectiveness of each of D&D's four basic types was determined in large part by one character attribute -- a different attribute for each type. I contend that this attribute was in fact a gameplay-driven abstraction of an archetypal pattern of behavior of characters in fantasy literature, which was based on heroic mythology, which in turn was a way of highlighting the behavioral styles of real people and their distinctively different ways of understanding and living in the world.
The correspondences between the four fundamental character classes and their controlling attributes are as follows:
(Constitution and Charisma were the two other primary attributes of characters in D&D, but they were not used as defining/controlling attributes for any class.)
It's easy to see how representing each of these four attributes with a number leads immediately to gameplay. But it's important to also see that each of these four attributes is an abstraction of a different personality style, and that part of the fun of playing a character whose abilities are determined by their "class" is playing with the stereotypical (but fundamentally realistic) patterns of behavior we all recognize in those styles.
A Question of Style
Strength, Intelligence, Wisdom, and Dexterity each signify a different way of understanding -- and thus interacting with -- the world.
Strength represents the preference for attacking problems head-on, for directly pitting force against force. The archetypal Fighter prefers to keep things simple -- follow the rules, do your job, be compensated fairly, enjoy the rewards of success.
Intelligence is the hallmark of the Mage, whose prefers to solve problems by understanding them and applying the correct tool in the correct way to their resolution. Knowledge and understanding, represented in fantasy literature by mastery of the arcane arts, are the mage's preferred way of approaching the world.
Wisdom is the Cleric's goal. Wisdom, perhaps best understood as intuitively living in harmony with the world, wants all the beings in that world to live in harmony with their nature and with the overarching principles of rightness. The ability to heal others in both body and soul is a natural interest of this archetype.
Dexterity in any situation is the distinguishing feature of characters representing the Thief. Not only does this permit them to use tools with surpassing skill, it also defines a particular kind of worldview in which plans and rules are unnecessary. They're not nearly as much fun as making things up as you go and counting on your nimbleness and adaptability to get you out of any trouble.
By closely keying each of the abilities associated with a class to the archetypal features of the character attribute that defines that class, D&D accomplished two things.
First, it made roleplaying easy and fun. In a purely utilitarian sense, having characters with distinctively different kinds of abilities made the whole group better able to deal with different kinds of problems that could be encountered in the gameworld. But perhaps more importantly for a roleplaying game, when you played a mage character, the abilities of that class encouraged you and helped you to play that character in a way that "felt" like pretending to be an exemplar of that kind of personality style. Recognizing the distinct personal style that was represented by the class helped one to enjoy playing a character of that class.
Where We Are Now
That brings us back to today. In the decades-long process of transitioning from Strength/Intelligence/Wisdom/Dexterity to Fighter/Mage/Cleric/Thief, and thence to tank/DPS/support, we've lost several important things.
Most obvious is the loss of the Thief class, which represents the Rogue archetype. While letting players express this kind of "loose cannon" archetypal behavior through their character abilities might appear to be problematic in a PvP setting, eliminating it means losing access to both the fun of playing this risk-taking kind of character as well as dexterity-focused problem-solving techniques that can get your group out of a jam when nothing else will. What would Star Wars have been without Han Solo?
There is a more important loss, however, which is the understanding that these roles were once archetypal. Without that understanding, the implementations of these roles no longer link as strongly to the mythic archetypes. They can still be fun in a surface-level, number-crunching, mechanical kind of way -- tank attracts aggro, mage does damage, support class provides healing and crowd-control. But the deep joy of playing a "role" in the artistic, literary sense of expressing the behavior patterns of an archetypal pattern represented over several millennia of human mythology, is gone.
Into the Future
MMORPG developers can retrieve some of this fun by recognizing the human archetypes on which roles and classes are based, and by consciously designing the character abilities and gameplay content of their gameworld to once again express those archetypal styles of understanding and interacting with the world.
Tank/Fighter types and the game content associated with that style can be focused on the direct application of force, on collecting loot and badges, on simple leveling, and generally on the enjoyment of knowing the basic rules of play and following them for profit.
DPS/Mage characters and the content created for them can be developed to apply knowledge and perception to solving problems. The character's level of capability should be affected by how much the character knows about the gameworld and how well they're able to integrate that knowledge to respond to novel situations.
Support/Cleric characters and their content can be designed to highlight the importance to this archetype of wisdom in resolving problems of body and soul. Beyond healing and crowd control, this role could be much more interesting to play with the restoration of the understanding that it's based on an archetypal representation of the personality style that cares about other people.
And bring back the Rogue role! :)
The mythological bases of the tank/DPS/support roles prominent in today's MMORPGs appear to have been forgotten by their designers. While this is fine for a purely mechanical, numbers-based, follow-the-arbitrary-rules kind of game, it should be understood that the price tag for this approach to MMORPG design is high: players lose the joy of expressing their in-game actions as heroically distinctive characters. It's just about doing a job.
Archetypes link player behaviors to the heroic myths and legends of human history. The archetypes (along, of course, with the game's setting) should drive the abilities created, rather than abilities being generated without thought for consistency with playstyles. Recognizable patterns of behavior and diversity of problem-solving modes are directly connected to perceiving differences among playstyles as reflections of archetypal preferences. When roles aren't understood as reflecting distinctive playstyles, the abilities created for those roles feel generic; they're not as much fun.
Abilities should instead be designed to help players express archetypal behaviors. By returning to the roots of character ability design, in which the things that characters can be good at are structured around the fundamentally distinct attributes of legendary heroes, MMORPG designers can restore to players the pleasure of heroic play beyond mere number-crunching.
And once character abilities are focused on playstyles, the roles derived from those abilities will feel vastly more satisfying. The better that game designers can tap into those fundamental heroic archetypes, which haven't changed since the days of Homer's Iliad, the better their game will resonate with gamers looking for a heroic experience.