If you take people from opposite ends of the spectrum and put them in a well moderated environment, the discussion that results often helps you to appreciate the different angles that people approach political issues from. Aside from in the U.S. during recent years, political issues are usually a matter of perspective and shades of grey. i.e. If there is a black and white scientific consensus on a given topic, it rarely becomes a political topic (except recently in the U.S.). It's when people with different opinions explain their position and try to sway each other that you're most likely to see arguments that actually have some merit. Even if you are not swayed by an argument, at least you can get a sense of why somebody with a different perspective sees the issue that way.
Unfortunately, at lot of people, and I'll leave it up to others to speculate on who those predominantly are, are not curious about or interested in views that don't align with their own. They may perceive exposure to such views as aggression. i.e. If you express a view they don't agree with, they may see it as an attempt to force them to align with that view. This perception of persuasion as aggression may explain why some scientifically black and white issues have become political.