So what is it that an Archaeologists does? do they "dig-up" the past? Through a myriad of different methods, which I can state with confidence I don't know the number of, Archaeologists look at physical evidence, support it with the written record when possible and other research, when possible, to support an almost certainly unprovable hypothesis about people and events which took place at some location in at some point in the past.
That's what archaeologists do in the field, but not really how they contribute. At the end of the day, writing is how an archaeologists contribute to the academic community and the world at large. This means that any archaeology student who wants to contribute to the archaeological community needs to be able to write, and write clearly, concisely, fluently and honesty.
A professor of mine is fond of saying that archaeology is destruction, and I believe him in many cases. There is no such thing as re-excavating the same holes, what you do is destroy the provenience and orientation of the artifacts as they are removed. You destroy a site in small increments and in it's place you leave a report. That, with the material culture of course, is the legacy of Archaeology. The writing is far more important in most cases however, because in reality though most artifacts don't end up in museums. There are far more tiny sherds of ceramics, stone flakes and rusted unidentifiable pieces of ferrous metal that can't be identified than there are statues, projectile points and vessels.
That means if you want actually want to be a good archaeologist, one that makes contributions to the community your part of - you need to write and write well. A good archaeologist is a good writer and that's why I'm writing this. To practice expressing my thoughts clearly, concisely, fluently and honestly. That is my reason to write.