Contemporaneous is currently one of my favorite words. In all honesty it's as much because of how it rolls off the tongue as what it means but for the purposes of this post let's assume that it's just because of the latter. For the most part contemporaneous communications is how we interact with others of our own species, both verbally and nonverbally. It's typically pretty honest and certainly it's colorful, filled with emotion, conviction and exuberance, but it's usually not very well organized and because of that I believe that it tends to be less powerful than structured communications especially when it comes to the written word.
As a case in point consider a speech like Lincoln's Gettysburg Address. Clearly it was written in advance and undoubtedly went through at least a couple iterations before Lincoln felt that it was "ready to go". As a result of that process the message was powerful and it is one of the most beloved speeches in American history. In just ten sentences that took approximately two minutes to deliver Lincoln framed the war and memorialized the tragic loss of life so "that these dead shall not have died in vain". Now compare that to virtually any email you have ever written or read and I think that you'll agree that the differences are astounding.
I'm not saying that email or any other written contemporaneous work can't be powerful or profound but by the nature of how we as humans construct our thoughts (again a generalization) it's just less impactful. Think about it. When was the last time that you cried as a result of an email you received. What about being frightened or impassioned or furious? Now think about books, novels, short stories, plays, movies, and poetry. I can recount incidents of strong emotional response in each and every case and not just on occasion but rather fairly consistently. Of course not all text and for that matter, authors, are created equal, but in the scope of things I believe that it's true that structured communications outshines its contemporaneous sibling when it comes to impact.
Where contemporaneous communications shines is in establishing rapport and creating an intimate touch point for individuals to connect with one another, even where the message is not pleasant to the receiver. It's entirely "human" and can be employed by anyone regardless of their station in society or educational background. As a matter of fact the only significant impediment to the success of contemporaneous communications is the language barrier. Most people it seems can get past the cultural barriers that exist, to a greater or lesser degree, if the dialog is conversational in tone and nature but not so much if the conversation takes too formal a tack. Conversing contemporaneously, while probably not the most impactful, is certainly the most human and with out a doubt the most fun.