... merely "a pile" of writing.

What a great expression, and something I have often felt as I did portfolios. Portfolio implies a cohesiveness, as well as a breadth. It’s inclusive (it has borders: writing done in a class, in a year, in a profession) but it is also expansive; more than one piece, more than one draft of one piece, more than just the piece itself (it expands or transgresses the traditional borders of the classroom). We should, however, remember that portfolios can become a form unto themselves, and in some ways they already have. If reflection is as key an element as the authors suggest here, I find that limiting to the form a portfolio can take. What’s wrong with a portfolio without reflection?