Earlier quoted context omitted.
I wish it was more standard where I live (Canada)..
I'm actually not a fan of it. Granted I've mostly driven older cars, without the wonders of ABS etc - but most situations that require heavy, unplanned breaking for me, are also times I really should have two hands on the wheel. I'm not fundamentally opposed - systems that do it automatically sound like a fantastic compromise. I just think if it's dangerous enough that I feel other drivers need more warning than norm…
Then, switch on the hazards so the driver behind you gets a heads up. Obviously you don’t risk crashing fumbling for the hazards.
Particularly useful on rural roads with many turns where the slowdown really might be surprising, or on off ramps where the car behind you might not have arrived yet.