Direct quote 1998
“designs that are "dishonest", weird, or that are just meant to be visually stimulating—like female characters with huge busts (laughs)—I don't like those. I wanted characters who, just from looking at their clothing you'd be able to tell what kind of person they were, and what their motivations were.”
What it documents
When asked in 1998 what he wanted from the characters in Metal Gear Solid, Kojima answered “hardboiled”; he said it is a serious, heavy story and he wanted characters who could hold up that world, and that he dislikes “dishonest” designs—weird or purely visually stimulating ones, like female characters with huge breasts—and prefers characters whose clothing alone lets you tell what kind of person they are and what their motivations are.
Source
shmuplations.com; MGS development interview in The PlayStation (1998), unofficial English translation. View source ↗
“Hardboiled. It's a serious, heavy story, and I wanted characters who could handle that world.”