As the Waltz evolved as an accepted dance in the late 1700s, it allowed partners to dance closer together. Since then (for centuries) dancers have been working on perfecting the art of two-headed four-legged movement (partnership). Originally Ballroom Dancing was just the Standard/Smooth dances. At the time, there weren't any formal Latin/Rhythm dances. As the Latin American and African rhythms became more popular, the Latin/Rhythm dances were formalized. The definition of Ballroom Dancing was then expanded to include the Latin/Rhythm dances.
Throughout the history of Ballroom Dancing, dancers have been developing methods to accommodate two-headed four-legged (partnership) movement. As Ballroom dancing evolved the methods of leading and following changed. Early on, men basically muscled the ladies around the floor. As Ballroom progressed, a little more thought was used developing the lead and follow concepts of partnership dancing. There are rules for two-legged movement (single person moving) and there are rules for four-legged movement (a partnership moving). The physics and geometry of the two-headed four-legged animal movement was starting to be considered. Just as there are laws of physics and geometry, there are laws (rules) of Ballroom dancing. The rules for Ballroom Dancing are just methods thought to be the best way to accommodate four-legged movement. These methods are constantly evolving and changing. At one time the leader used the fingers and heel of the right hand to lead promenade. This has since changed to the body of the leader being used to lead promenade. Currently the right hand does almost nothing as far as leading.
Everything we do in Ballroom Dancing has a reason (usually a physics or a geometry reason). There are no wasted actions. All of the actions of the dancers affect each other. One of the goals is to keep the communication between the partners as clear as possible. Any superfluous actions just confuses the communication process.
Beginning dancers are often very conscious about the using the rule for proper head position because they think it gives them an arrogant, snooty look. The fact is the correct head position is not for looks at all, it is for the balance of the two-headed four-legged animal. The head position to balance a two-legged animal is quite different. The correct head position to balance a four-legged animal is one of the Ballroom rules.
It is very important that the dancer understand the "Why" of every action (rule). If the dancer knows the "Why" he/she is more likely to do it. If your instructor asks you to do something and you don't understand "Why", ask him/her to explain the rule.
Here is an example. The instructor tells the student that the forward footwork for Slow Waltz is "heel, ball, ball/flat". The student responds "Why do I care, Waltz is just a 1, 2, 3 beat". The instructor replies. "The footwork defines the character of Waltz. Waltz has a swooping up and down feeling that is accomplished by the ball and ball/flat footwork. The first "heel" step initiates forward power for the movement, the second "ball" step creates the "rising" action and allows for the leg to swing through, the third "ball/flat" step creates the "falling" action and prepares for the next step".
When I teach men, I teach them the mechanics and the rules of the movement element first. I then explain the "Why" of each rule. I do this because men, in general, learn mechanically. Men in particular need to know the "Why" before they will do it. Once they know the "Why" they don't seem to have a problem doing it.
When I teach women, I dance them through the movement element first (because women in general learn by feeling) so they can see what it feels like. Then I explain the rules along with the "Why" and dance it again so the rules can be applied and new feelings developed. When I teach a lady a "forward lock step" element in Waltz, I dance her through it. The natural action for the lady is to open her feet because she is in "outside partner dance position". This causes an awkward forward movement feeling. The rule is to keep the feet pointing down line of dance instead of allowing them to open. I explain that this learned action (rule) allows the forward movement to be smooth and controlled. I then dance her through the element again so she can experience the new feeling with the rule applied.
I can't impress enough of how important it is for the student to understand the "Why" of what they are being taught. Once the student understands the "Why" he/she can coach his/herself on learning that particular movement element. The student is paying for this information, so don't be shy in asking questions. If your instructor doesn't know the "Why", maybe he/she should find an instructor that does know the "Why". Just like in physics "every action has a reaction"; in Ballroom "every action (rule) has a "Why".