I'm sure lots of people will argue that self-driving cars will, in the long run, save a lot of lives, and therefore we can justify some loss of life in the process. They are probably right about self-driving cars saving more lives in the long run, but I don't know that the conclusion follows.
From what has been released so far, this feels like a case where a human would have had a high likelihood of doing the same thing and would not have been at-fault in the collision. But self-driving cars have more sensors and, in theory, more capabilities to prevent something like this, and we absolutely should expect them to do better.
As someone with a little bit of experience with the machine learning side of things, I understand how this stuff is really hard, and I can imagine a handful of ways the system could have been confused, which makes it all the more important to understand what went wrong and how we could prevent it from happening in the future.
As self-driving cars become more prevalent, things like this will happen and it will be tough to walk the line between over-reacting to every incident and killing progress in this area and designing safe cars that don't make the problem worse. I think it is prudent to have Uber stop testing on public roads until they can explain how this happened and how they can keep it from happening again.