Your suggestion is correct, however implementation would require making entire combat system bit more complex (for example at least more direction of cuts just like IRL or in Jedi Academy or Kingdom Come). Again I support that aswell because I find Mount and Blade very symplistic and just servicable, however this already would cause uproar with conservative WB inherited playerbase. Once this is done, hitboxes for stuff like face, armpits etc could be added, however hitboxes would have to be reworked because currently they are inflated bubbles that overlap which makes stuff like angle based armor bouncing impossible (we know this because we attempted this) and sometimes puts hitboxes on wrong places (just try to find neck hitbox by shooting your soldiers, its much lower than you expect).
All of this would require company that is not afraid of "complex" and that welcome challange. Which if you spent some time on this forum, you already know is not the case of TW.