> HN should be able to tell the difference between good PR and good tech.
You know what? I make an exception to that in Elons case. There are plenty of people who do that and who leave us pretty much where we were before. Think of the tons of Microsoft Research projects that are mighty cool and are thrown in our face every half year or so... but never go anywhere expect right in the basket of "well, I guess Microsoft isn't entirely dead, yet" PR.
Is this extremely exciting stuff in itself? No. But it is still exciting to me because I know if Elon does it, he will follow up and make the best of the opportunity. It is the marriage between the person and the project - in the Microsoft example, some, probably mostly PR, division comes up with "oh, I suppose that's neat" on a regular basis, but what they do has no direct link to any real life implementation. What you need is that connection of being able to dream big and execute big - and for that, the impulse has to come from engineering, not PR.
It's like knowing that Carmack is hooked on VR goggles. For some things, the person doing the thing really makes all the difference in the world.