Why should a Paladin be a tank? Why should a rogue be a trap remover? Why can't the Paladin be an embodiment of his faith's wrath? Or a mysterious grizzled old general who leads a village in over throwing the bandit king tyrannizing them? Why can't the rogue be a con artist, or a second story man, or swashbuckler who don't know anything about traps? Why do they all have to be awesome in combat? Why can't we have a courtier who can defend himself, but really doesn't do much in combat, but can manipulate the system and call in favors and speak with a silver tongue out of combat? Or a physician and scientist who, while not helpless is not a combatant, can patch anyone in the party up, identify every plant under the sun, and knows pretty much everything about everything?