Fuck this.
In the United States the benefits of full time employment are mandatory if you want to live a much less stressful life. Tying benefits to employment has given employers far too much control over their employees lives, without a huge savings or secondary income source anyone without insurance is one bad day away from bankruptcy (and too many people /with/ benefits are as well).
If a 4 day work week lowers stress and increases productivity that much, I don't see why many industries shouldn't adopt it. And don't tell people that "You have a choice, just get a part time job instead". Thats not a choice, thats a financial death sentence.