As long as there are marginal gains to be made from working an extra hour I don't see this changing. Imagine if one country decided to change from a 40 hour work week to a 20 hour work week. If this decreases their GDP from producing less output, then they become economically weaker, their standard of living in terms of purchasing power is diminished, and the tax base is decreased. I think the biggest reason we don't see more leisure time is the same reason wild animals don't see much leisure time: competition. At the international level, countries which produce more are more powerful, and at the domestic level other things being equal an individual who produces more will command a higher income, which translates to gaining a bigger slice of the economic pie and the additional power that confers. I suspect many of the people on hacker news could easily live on half the income they make, but we choose not to, because we prefer the extra affordances of working full time or more.
It's just people being wired to compare their lives with other's. Humans evolved in small groups with hierarchies where your "rank" compared to others could mean the difference between life and death. Not so much these days, but the habit is still there.
Luckily, we also evolved big brains that let us override almost any instinct and with a bit of effort we can be perfectly happy with any slice of the pie.
P.S. I'm somebody that gave up a large fraction of my salary to be able to work part time and travel the country. It's been worth it so far.
This is fairly inconsistent with countries with riding inequality, such as the US. If anything, rising inequality shows that rather than there being a gradual curve of salary proportional to hours worked, there are tiers of salary and not much in the middle.
