I lived with a Danish family near Cophenhagen while studying abroad a few years ago. I wouldn't say Danes had "low" expectations as much as they had "realistic" expectations. For example, my 20-year old host sister and her family knew that she was highly intelligent and motivated from an early age, so she was put on the highest track of education in her early teens. My 16-year old host brother, however, knew he did not enjoy academics and planned on following a more vocational track in his early teens. Kids are not told they can "be anything they want," they're taught to learn their own interests and skills from an early age and how to use them to the best of their ability, therefore making them more likely to find fulfilling work.
Another huge factor I noticed in Denmark is the lack of the "Jones'" problem. It was the social norm to be very humble and not "show off", or brag about yourself in public. This was considered highly rude and kind of silly. Almost all houses I saw were small, most Danish families owned one car, if that, and of course they have a wonderful public transportation system. Not everyone I met fit this description, but it seemed to be built into their culture.
Of course Danes still have their problems, the biggest ones that I noticed being immigration issues & racism (party having to do with their high levels of national pride and "smugness" imho), and a high cost of living. But they certainly could teach others, especially Americans, a few things about living higher quality lives overall.