As I commented on the original article, the population distribution needs to be accounted for. As a percentage of the eligible players of adult SL for an age group, what is their usage pattern?

The average millennial (born in 1992, age: 16), is not old enough to log into the adult grid, the raw population numbers *cannot* tell the whole story.

If there are 5 million Millennials old enough to play SL and 25 million GenXers, the you should expect, on average, 5 times the number of GenXers.

I bet that distribution is more than enough to account for the difference without getting into the relative "creativity and appreciation for free-form play" of the two generations.