As someone suggested, part of the reason may be because they are hoping for a lawsuit.
But I think an additional reason is a little power trip:
"See me? I'm walking here. That means you have to slow down. That means you have to stop. I have the power right now. You need to do what I say. Because I am in control. So, I'm going walk really slowly in front of your car. While I stare at you. So that you know who is the master now, and who is the slave. How you like that whitey?"
Yes. That, too.
I’m concerned that this new law might also give some people the idea that is is absolutely all right to enter the roadway to deliberately stop a motorist for nefarious purposes (e.g. carjacking).