Lead writer for Bungie, Joseph Staten, has stated that “Immersion was the main goal” in creating Master Chief. In a recent interview Staten claimed that details of the chief’s past were left blank to add to a sense of player immersion.
“The less players knew about the Chief, we believed, the more they would feel like the Chief.” He further commented that “When it came to the Halo novels and other products of the expanded universe, immersion wasn’t as important as deepening understanding. Immersion was the main goal here. Also keeping the Chief a man of few words reinforced what we wanted to be a tough-as-nails soldierly persona.”
Staten also said that Cortana was originally intended just to point the chief in the right direction. Staten claimed that “we needed a character who could consistently guide the player through the game, and an onboard A.I. was something that could always credibly accompany the player (i.e., another soldier might get lost, wounded etc). Over time, Cortana became a fully realized character—a friend and companion to the Chief, not to mention the only person to poke revealing holes in his tough-guy exterior. Through his interactions with Cortana, the Chief revealed his humanity (e.g., players learned the Chief had a sense of humor when he banged his helmet to stop Cortana from talking). And it was for these reasons that we focused so much on the Chief-Cortana relationship.” The more we know.
Thanks to VG247 for the info.