[Tristan Lall]

I find that threaded mode enforces a sense of flow within the discussion. Time is of the essence, because it's somewhat gauche to post a comment about an early post late in the thread. That in turn makes it easier to read the thread and to refer to others' comments in the context of what has come before. Threaded view attracts comments on comments, and makes it harder to understand what was posted when.

By contrast, while I like the idea of a hierarchical display as a way of showing information about who responded to what, I don't think that metainformation is terribly useful to the ordinary reader. And if I ever want it, it's just a link away. (Note also that you need to enforce a particular way of using the reply buttons if threaded view is to be useful. You can't just quote people; you have to use the quote post button, or include a post number so that the software can parse it.)

Threaded view used to be more common long ago (especially with e-mail-based messageboards), but nowadays most forums use a linear view.