I have no idea. My best guess is that he knows as humans we are work-a-holics and we need a break also that we worry a lot so taking a sabbath makes us rely on him that it's going to be ok. When I have taken my sabbath I worry because I think "how will I get things done?" and then it's like "Ok I'm doing this for God, he asked this of me so I have to trust that it will all be ok even if it's not."
Does that make sense?
Just a shot in the dark here, but is much of this having to do with functionality, and by that I mean, "I need to support myself and I need to function in life, so sometimes I need to work on a sunday", for example? You put aspects of "work" and "obedience to God". Look, there are things we "should" do, but if we "can not", literally it causes more bad things were we to not rescue a sheep from a pit, if we "can not", "at times", Jesus has made clear it will be ok. Knowing you "should be obedient" is not the same thing as "drop everything and become a covenantist". It just does not mean that.
Again, I'll say, it appears at times I'm legitimizing "just do whatever you want", but I'm not. If it's something important, God knows it's important, He knows this in our hearts. He knows if we're "just making an excuse", or "if this is something that needs to be done". We're filled with original sin anyway, we can't help that, He knows that. BUT when you
can be obedient
you must be obedient, and
you will, because if you can ask all these things, you obviously "know better".
Is this closer to the truth you're seeking?