Less is More

Casting of Characters
Whether a player starts with just an array of six attribute sums or with a character sheet full of skills, feats, backgrounds and statements that the character believes are true, the player must breath into the imaginary being whatever life it will have. How each player approaches this element of character development is determined by how they play the game. Do they prefer to preconceive the character, imagining what they are like ahead of time, or discover who the character is through play? How fleshed out do they like to make their character? Are things like height, weight, hair color, eye color and dress important or insignificant details?
A frequent complaint I hear from players concerning White Box characters is that all fighters (clerics or magic users) are the same. Are they? Mechanically yes, they are very similar (magic users less so because of their unique spell books), but thematically they can be as diverse as one's imagination can make them. As with many aspects of old school systems, less can be more.
One of my favorite experiments for illustrating just how different characters can be using just three classes and all being human is to ask the players to imagine a person from a set of six attribute scores. High strength, low intelligence, or average across the board, give them a name and tell me who they are, often using a modern(-ish) setting as default. Now I whisk the characters away to a fantastic medieval setting and assign each a class - Fighter, Cleric or Magic User. Wow, are those characters different and unique!  Every time I have done this, my players have developed well defined characters whose personality shines through during role-play and whose identity is only marginally dependent on the class they choose. I think it illustrates nicely the potential in developing interesting, and unusual White Box (OSR) characters.
Contrast this with a player looking at a detailed multi-page character sheet from a game with a more structured chargen mechanic and they are likely to announce, "This character seems to be good at fighting, library use and picking locks." They are apparently front-line fighters, useful book investigators and handy to have for breaking and entering, but who are they? What do we know about their personality? Perhaps the player will creatively imagine something that connects those seemingly disparate skills together, or maybe they will just play the character and see what personality traits emerge during play.
The nearly blank slate that White Box gives the player on which to develop their character seems to provide more freedom to individualize each character, and although the game mechanics may not reflect each character's uniqueness, the role-play of the player can.