Marketers need Sociologists. Actually, marketers should be Sociologists (or Sociologists should be marketers).
When I was getting my Masters in Sociology and Anthropology in the late 1990s, we took on some interesting studies regarding interactions between people in online forums. Online forums were in their infancy, but that was at the time the social networking activity of the day. One of the things that we noticed -- long before it became common knowledge -- was that when a user made a recommendation in a forum post, that product/cause/website/song/whatever got a lot of attention from the group. Today we know that users have the tendency to trust peer recommendations significantly more than advertisements for the same product. Personally, I think the "Like" button is overrated, but recommendations, in general, are not. We all find ourselves taking a closer look at products that have been recommended to us. We ignore the ads until they coincide with those recommendations. We trust our friends more than ad agencies.
There's no surprise there. However, keep in mind that Sociologists noticed this trend had economic significance in online circles long before the market did. People act online as they do offline, and Sociologists study people in both worlds. We are all social creatures (most of us, anyway), and we like to share our opinions. Sociologists, as social scientists who study how groups act, react, follow and lead, have tremendous insight as to why trends are happening, their theoretical background, where they may be going.
Sociologists can provide a perspective regarding preferences by gender, cross-cultural marketing, ageism in advertising, and even the economics of social networking. Studies have been conducted on many of these topics, and marketers tend to avoid reading them. Sociologists love them (most of us, anyway). Having a Sociologist examine marketing trends is something that has not been common practice among companies, but it really should be.
I will be the first to admit that academic studies can often be outdated when it comes to trends in technology. It takes a long time to complete these studies and by the time they are published, sometimes that technology has moved on (see studies on MySpace and Friendster). But if the study was of any value to begin with, it will point to human behaviour, and much of our behaviour hasn't changed for thousands of years. And what has changed, can be understood and translated into economic value.
Do not misunderstand what I am saying here. Marketers read studies as well. They conduct them, albeit in a very different manner, stressing quantitative surveys over qualitative observation (that is just too time-consuming). However, their perspective is incomplete without the assistance of other disciplines (arguably, Psychology is no less important). So in a perfect world, the Sociologist will analyze the social trends, while the economist/marketer provides the economic and purchasing trend. Together your chance of increasing sales is greater.
As we build websites, a marketing tool in itself, we try to understand the users' (as a group) behaviour and how our websites will influence the masses, because we want your product/cause/website/song/whatever to be recommended by as many people as possible. To do that, you need to understand people. And Sociologists can help.