This is an interesting question. My first impulse is to say that there have always been more dystopian stories than utopian stories. From the book of Revelation to Mayan tales of the end of days, we have a rich history in doomsday tales. While Sir Thomas Moore's Utopia is held alongside Dante's Paradise as an example of utopian literature, these works have many counterparts and, it would seem, have been historically overwhelmed by those counterparts. We might also consider the notion that works of utopian literature offer visions of extremes in society which are often seen as being dystopian.
Utopia is the name of a highly authoritarian society that suppresses individualism and private property to secure the collective good.
We might consider Brave New World in this light as well.
The question then is might be asked with an eye to why we have always been intrigued with dystopias in story-telling in preference to utopias. This view may allow us to consider the broad and timeless appeal of the dystopian tale as opposed to the culturally relative appeal of dystopian literature.
Considering the premise that dystopian literature has always been the more popular of these two modes, we might argue that attempting to discern culturally relative reasons for our current interest in dystopian tales may actually lead us to misapprehend the basic appeal of such stories.
Another interesting idea to note may be the shifting types of dystopian stories. We might see some symbolism across the dystopian mode in the "vehicles of disaster" that are featured in this stories. Today zombies dominate the dystopian landscape. Fifty years ago, most of these stories featured technology gone wrong. Supernatural terrors and natural disasters once seemed to be more prevalent than they are today in dystopian literature.
What do these various images of social decay signify about a culture? That is another question we might consider in this conversation.
These days it seems like we find more dystopic literature than utopic literature. Perhaps the reason for this is that we are constantly bombarded with negativity in our society. Turn on the television or radio news, open a newspaper, or check out the headlines on the internet and most of the stories that one will find seem to be negative.
Whether it's war in the Middle East, unfavorable economic conditions, arguments over abortion or gay marriage, we are constantly assaulted by negativity. Is it any wonder that writers craft works like Hunger Games when the world around us seems to be filled with nothing but disaster?