That's my thought with it as well. I have owned a Prius and currently own a Leaf which uses a similar setup. They made the shift setup different enough that you don't have muscle memory competing with you. Making the shifter look the same but work differently is stupidity of the highest level. And with the whole thing being electronic now, just make the car automatically go to park mode if the engine is off, driver door is open, or the driver is not present. Simple software update as all the required sensors are already there.
Yes, people should use the parking brake. But they don't. I even had a driving instructor get after me for using it, he said it was "unnecessary". So it's not surprising that people don't do it. The vehicle should have basic fail safe setups. Make it possible to override, but have big warnings and noise if they do. If a distracted user can easily miss that the vehicle is not in Park mode with the engine off or doors open, the UI has a serious flaw that needs fixing. We all agree drivers shouldn't be distracted, but they are. Everyone gets in a hurry or something once in a while.
While a death as a result is tragic, I don't think it rises to a fault of the manufacturer that should result in legal action. With the current courts and laws though, it probably does. And the lawyers involved will get millions, affected owners will get a coupon for a free oil change or similar.
Frankly, we wouldn't even be discussing it if it hadn't been a famous/rich person who was killed. Sad as that is.