Combat Roles

I believe that roles improve the overall experience of a game.  I always think of combat roles in terms of football positions, you are part of a team.  However my number one philosophy, in any game, is freedom is most important.  That is why I don't like pre-defined classes.  Players should simply pick armor, weapons and utilities that help them fulfill the role they want.  This creates an open system, allowing players to be creative.  It allows them to experiment and produce truly unique builds.  While there is potential to create truly terrible builds; respecing is easier since you don't have to create a whole new character, you just change your gear.

I always hated being a healer or tank in player versus player combat.  Being a healer meant you just followed around the strongest damage dealer, trying to keep him/her alive.  You were never able to do anything yourself.  Being a tank was worst, their only role in PvP is punching bag.  You guard the flag and try to stay alive until the damage dealers arrive.  I think all players should deal, relatively, the same amount of damage.  The difference is, a player who specializes in dealing damage is better able to deal damage.

Quick example.  All players pick utilities that help them fulfill their role.  A tank may choose a shield while a damage dealer may choose a flamethrower.  Attacks with their weapons will deal relatively the same amount of damage.  The difference is that the damage dealer can set the enemy team on fire while the tank can shield said flamethrower attack.  This allows tanks to participate in the fun part of combat, killing other players.