HackerNews is an echo chamber for pessimists guised as realists.
You see this in threads ranging from FB, Uber, Bitcoin, Tesla, people showing off weekend projects, etc.
It's a common phenomenon and in mainstream culture we call them "haters".
Now why it was disabled is another question. Most likely because their system isn't anywhere near ready.
The only value I see from the whole of Uber is know how and practical examples of how not do solve this. The fatality didn't change anything, it is (and was) painfully apparent that it was only a matter of time.
Oh yeah, and Uber released a super contrasty picture to justify their car's behavior. Less biased sources showed that there was plenty of visibility on that stretch of road.
If you're looking for sources, Ars covered everything in pretty good detail.