I work an 8:30-5:30 job and this ensures that everything I need to do outside of work during normal business hours builds up to consume my weekend. I know several people who work for business with half-day Fridays and that's when they get all of their outside-of-work things done ensuring that their weekends are actually free for doing the things that they want to do.
If you have kids this is an even bigger deal. If you don't, you're free for whatever every evening. If you have kids, your after work time is committed until they get to sleep every night. Having that work-day time when your kids are in school becomes HUUUUUUUGE.
I also know people who work for CVS doing 12 hour shifts with a limit of 80 hours over the course of two weeks. This leads to a lot of full days off every 2 week period...and they love it.
It's less about the "X hour workday" and more about the "X hours of free time during regular working hours"