You should categorize because someone people wouldn't care about certain issues but will fight tooth and nail for others.
Like us being entrepreneurs, we would have an opinion on "fast fail", so we would want to get to these topics more quicker than something related to politics or sport.
Categorising allows you to focus resources on which categories drive the most traffic to the site.
Also, try to be more specific in seed content. Having broad topics thesis doesn't make for good arguments. For instance "which team is better Lakers or Celtics", may become "which team would win 2010 champion-Lakers or Celtics". It's narrower and more focus which makes for an easier argument. Broad categories require much wider and deeper knowledge to begin to address the debate.