I guess Michigan could pass a law requiring landlords to accept rent payments every day. I'm not sure anyone would actually want that as a reform.
So… I don’t get it. You cannot enforce 48 hours unless the repair is requested less than 48 hours before rent is due.
I guess the question becomes - can you bill your landlord if you are forced to live outside their property, and deduct that cost from rent? If that's the case, the withheld rent becomes a means by which you can immediately recoup the cost of housing outside the rental unit.
Even then, just the threat of non-payment is a big deal for a landlord who is - themself - likely paying a note on the property and at risk of default if they can't use your money to pay their own creditors. The possibility of missing a mortgage payment creates a natural incentive to fix the property sooner rather than later.
As it stands, this would be a significant improvement to landlord/tenant relations. Which is why it likely won't pass.