The idea is obviously appealing, but is a pipe dream to which employers will never agree. Employers don't care about one's utility over a lifetime, because they only have access to laborers for a finite period of time. (In most cases 3-6 years.) Employers thus want to maximize utility in the short term. Fewer hours means less work and thus companies have to lower salaries, which may make this untenable for workers, and hire more people to compensate for these reduced workweeks, adding to fixed-costs like healthcare and making this untenable for employers.
Would it be great to spend more time with friends, sleeping or otherwise pursuing leisure? Obviously. But the labor market doesn't care about one's happiness (and the companies that do institute "leisure cultures" usually explicitly state that they do so simply because it increases productivity. In this case, companies don't care about you for your sake, they care about you for their own sake) and pursuing it comes at a loss of compensation.
Would it be great to spend more time with friends, sleeping or otherwise pursuing leisure? Obviously. But the labor market doesn't care about one's happiness (and the companies that do institute "leisure cultures" usually explicitly state that they do so simply because it increases productivity. In this case, companies don't care about you for your sake, they care about you for their own sake) and pursuing it comes at a loss of compensation.