Adventure Travel - the Arctic is still not on the map

In a sampling of adventure travel top ten lists, the arctic north never once appears! Moreover, across the lists, Antartica appeared only once. Why is this?

What could be more adventurous than a trip to the desolate north? What could be more unique than to set foot where few, if any, have ever been before?

While surface travel to the North Pole is new, air based tours have existed for a few years now. In 2005, more than 150 travelers reached the summit by helicopter and many more by ice breaking ships. Are these not considered adventures?