I'm afraid this is a very rosy way of looking at things:

* You can't simultanously work less and spend more. Working three days a week means consuming more leisure, but fewer goods. Spending would not go up.

* The lump of labour fallacy means that this doesn't have an unambiguously positive affect on empoyment.

I personally support flexibility working hours (then again, I would, because I earn enough that I don't need to work full time). But we shouldn't assume there are no trade offs at stake.