Inside and Outside the Lines

The difference between formality and politeness is often a point of confusion for those from relatively informal cultures. On the other hand, those who have been brought up in relatively formal circumstances often experience discomfort and even, over the long-term, disenchantment, in less formal circumstances.~Wikipedia "Formality"

As the personal letter is a form of communication that can be described as a slow motion conversation, perhaps the question that must be asked is how much formality is needed within a conversation. As communication is a matter of function, one must ask if the situation of the personal letter between friends is in need of any formality. Kicking out a predisposed framework can lead one to feel helpless. But this does not seem to be so with the letter.

The difference between formality and politeness is often a point of confusion for those from relatively informal cultures. On the other hand, those who have been brought up in relatively formal circumstances often experience discomfort and even, over the long-term, disenchantment, in less formal circumstances.

If history as anything to show about this, the personal correspondence between people (without severe psychiatric issues, and I do not mean that in a snarky way) has always seemed to follow a general structure, most likely based on the desire for receiving the information as quickly as possible.

Then again, one can have a great deal of fun painting outside the lines:
http://www.lettersofnote.com/2011/10/case-of-difficult-dressing-gowns.html