Hideo Kojima isn't letting the designs of Metal Gear Solid characters happen willy-nilly, you know. There is purpose behind their design...and that purpose is to be, um, erotic? Erotic is good for cosplay and sells figurines, apparently.
Straight from the man's Twitter feed—note that "Yoji" refers to Metal Gear Solid V's art director, Yoji Shinkawa.
Kojima went on to muse over memorable characters, noting one should be able to read a character by "observing his/hear silhouette, and the way he/she walks"—if the character is good, that is. So, he's obviously thinking a lot about character design, even if some of his goals with said designs raise some eyebrows.
Now to see if Metal Gear Solid succeeds on this front/what kind of context we'll be seeing sexy characters in...and later, of course, whether or not any cosplayers brave Metal Gear Solid V characters.