It can be useful if you've got the saw set up as an island, there's no cord to either dangle from the ceiling, or trip over on the floor. An island setup is super practical for material handling.
If the battery can get you through a useful number of cuts, yeah, it has some real advantages.
Losing a mains "all stop" (and a mains breaker at that) seems to me to be an odd safety choice.
I think cordless tools make a lot of sense for anything you have to hold or direct with motion. I'm just not convinced by the need elsewhere, particularly on the most dangerous tools.
That's interesting. I wouldn't walk over to the door to isolate power before changing a blade, for instance, I'd just unplug the cord or the battery. That lets the rest of the shop continue running while I have my hands inside the one specific machine.
I did say "additional", though.
I mean, yes, you'd want to be able to locally isolate the power as well, where possible.
But when the device is capable of running cordless, you're losing that scope.