Re
Jon,
This is a role-playing game to me. The role-playing comes before the rules.
What does this mean? It means I try to get into the spirit of what the person who created the original class set forth rather than the meta-game rules governing it.
The Paladin class was made to simulate the legendary holy knights of medieval style legend. Thus, Sir Galahad, Charlegmagne, and other such knightly types.
They are supposed to the ultimate champion's of good. The closest comparison's I can come up with are all literary because there are no Paladin's in the real world unless you want to believe Jesus was ultimately pure and give him a sword and some armor. That would be a Paladin.
A Paladin is ultimately virtuous and free of sin. I ensure this beyond the rules when I run my game. If you want to be a Paladin, you cannot be some fighter who just decided to be a Paladin. You have to have a Paladin type of personality, and I use literary means to determine this.
Just because 3rd edition genericized the Paladin doesn't mean I as a DM can't still have stringent requirements on their code of conduct. Even I admit in the previous editions of D and, Paladins had a much stricter code to follow, and thus more of a justification for why they received their powers.
Still, I would not even play this game if all I did was play by strict rules. Even in combats, I make sure to give my players some latitude for doing cool stuff they may have seen in a movie or throwing in a little divine intervention in the form of luck to help them to survive. It's an RPG, arbitrate it like one.
By your literary example of saying only ONE remained a Paladin doesn't that hint to you that that definition of Paladin shouldn't be a Core Class?
I am saying that a Paladin is a core class because a person who becomes a Paladin is more often than not born to be a Paladin. A person who becomes a Paladin usually lives those ideals while growing up. They are and have always been the ideal example of a Paladin throughout their entire life just like Galahad and Launcelot. They are the best living examples of what a knight should be and they were from the day they were born.
That is why I feel a Paladin should be a core class, though I can see why some would believe otherwise in this currently jaded world which so strongly supports moral ambiguity.