If this is a "nudge nudge wink wink we don't really work 40 hours when we're working from home" kind of thing, then why make the pretense of working 40 hours?
I value my integrity. When I say I'm working 40 hours, I work 40 hours. If "working from home" is implicit permission to lie about how many hours you work, then that creates a system where dishonesty is rewarded and honesty is exploited.
And if it's a "it's a little nicer to work from home" thing, then I'd say, not really. I would actually rather not work from home--my home is my space, where I can de-stress and do what I want. I currently work at a job where I "work from home" and I actually have an office I rent for myself so that when I go home, I'm actually not working.