Andrew,
The no-table idea might be fine for openacs.org, but remember forums is a general use package. Not just for the developers at openacs.org. The colors and table, I think, are helpful design elements. Also, pretty much every other bboard software I have seen uses this design :) People seem to like it.
What we really need is pluggable display templates so that we can have an option in forums instead of making everyone hack the templates.
