No one enforces the laws we currently have
That’s sometimes actually a good reason to change. It shouldn’t be, but a new law or change gets more attention both from the public and enforcement, whereas existing laws can become pretty much invisible and forgotten.
Rule 163 and associated are too wooly, too much is left to the judgement of the driver. “plenty of room” is absolutely meaningless really and “as much space as a car” is open to confusion (people think it means “allow as much space between you and the bike as you would allow between you and a car”). It’s like making the speed limit “Go at the speed you think is appropriate”
I don’t think you can seriously argue that it’s not easier to make a case, when someone passes a foot from you, that it’s less than 1 metre, than whether or not it’s “plenty of room”. Both in court and in conversaation
Not necessarily saying this proposed change is perfect; I do think it’s better. But basically definition of “plenty of room” is what’s needed imo.