I think that when we say "moderation", it can mean two very different things.
The moderation which is usually refered to could be called ideological moderation. Basically, it can be measured as the deviation between a considered community's median political position, or more generally what is considered the "mainstream" opinion. Ideological moderates are, to put it simply, people who have more or less as much people to their right than to their left. And ideological radicals are those whose positions contrast sharply with the average. As a result, it seems evident that what we define "moderate" depends on the group you are refering to. That's actually a main source of misunderstandings here between american and european posters : people like me I usually considered as the forum's "radical left" despite the fact we are almost centrists by european standards, while Franzl, who's often portrayed as the forum's official moderate hero, is a staunch right-winger for Europe. However, it's important to note that the reference unit is not necessarly a country. For example, people who are raised in a very conservative community can be surprised when he enters in contact with other sorts of people and discusses with them : he can consider that every people he meets is a radical leftie because the moderation standards of the people he uses to live with are far to the right of those of the whole country.
IMO this kind of moderation, by its nature itself, can't really be attributed to a particular demographic group. Of course, at a country level, you can identify "swing demographics", people who align more often to the mainstream. I don't think it is really connected to wealth, quality of life or high education. If you have to seach the most moderate demographic groups, you might (that's just a guess) find that they correspond more or less to the median demographics (people close to the median income, etc...). But is it really something important ? For a politician, yes, but not really for someone who wants to understand the influence of environment on behaviour. I know that's pretty lame to say, but everything is relative when it comes to ideological moderation.
Now, there's the other kind of moderation. For lack of a better term, I'd call it rhetorical moderation. It is basically the way one expresses his political opinions, how much violence he puts in his words - and sometimes in his acts - when it comes to politics. Rhetorically moderate people are those who discuss politics quietly, who don't consider people of different opinions as "enemies", who is able to make friends on the opposite political side. They are, basically, the "good people" in politics, those who don't need to insult their adversaries to win a debate. Rhetorically radical persons, instead, are those who demonize other ideologies, who spread bad feelings, etc... It may sound a simplistic categorization, but it works and is useful.
So, when it comes to this form of moderation, I think it is somewhat linked to social, economical and cultural environment. Rhetorical extremism is often a sign of rhetorical weakness : you start insulting people when you have nothing more intelligent to say. And it is undeniable that a stable situation, an equilibrate life and a strong access to culture allow you to develop a coherent political thought, which is the strongest barrier against hatred. Thus, I agree there.
The reason why the concept of "moderation" is so problematic in political discourses is precisely the confusion between these two forms of moderation. Which have, in fact, nothing in common. Since ideological moderation is always relative, there would be nothing surprising to see people who are ideologically very radical, yet perfectly moderate in their rhetoric. Yet, most people still believe moderation is always the same thing. That's a source of a lot of misunderstandings in the debate. Ideological moderates tend to justify their political positions by the fact radicalism means lacking respect, objectivity, being a hack... On the other hand, we have all the rhetorical extremists justifying their hateful rhetoric with Goldwater's quote (which makes sense when it comes to ideological moderation). Both arguments are logical fallacies due to the fact a same word is used to describe two very different things. Also, ideological moderation is indeed, as Barry said, not a virtue, and the most radical opinion can very well be the right one (look at the slavery debate). On the other hand, it is my opinion that rhetorical extremism, when it reaches some point, is inherently bad and condemnable whatever are the political positions. Eventually, it is a sign of weakness, lack of self-assurance, and inability to develop a coherent thought.
It is undeniable however, that there seems to be some correlation between ideological moderation and rhetorical moderation. While there are many examples of the contrary, it's undeniable that a majority of rhetorically radical people are also ideologically radical. Communists in postwar Europe or today's teabaggers show it quite well. While it's hard to identify precise causalities, my opinion is that the addition some factors (lack of knowledge, culture, etc...) and of life in a particular community whose mainstream view is different from that of the mainstream, can lead be a factor causing both forms of radicalism. Finally, the frustration caused by living in a country which holds mainstream views somewhat different to one's own can also lead to develop a more hateful rhetoric. Being in a minority is always difficult and this can lead you to think you are better than everyone else. That's why people can start developping a hateful rhetoric or even conspiracy theories and all...
Wow, this is probably one of my longest posts ever.
