A lot of them can be solved. Knowing which ones can be solved economically is the whole point of Elon Musk's First Principles approach.
(I should apply first principles to games and simulations.)
Are you seriously implying that landing a rocket is an unprecedented step in that direction?
Do you think something like this would have been impossible if people had set their minds to do it, in the 60. I don't think so. I mean, we had missiles that could follow and destroy jets moving faster than a bullet...like, I don't know, 30 years back? Exactly that is why I think this is just marketing and PR (Not the actual stuff they are doing, but how it is seen and projected)...
It would have been impossible. They just didnt have the materials science to build lightweight engines, fuel tanks, landing legs and such. The computers needed to control the rocket would have been the size of a large building and have to be on the rocket to be responsive enough. Remote control wouldn't have been an option. Also GPS didn't exist and no contemporary positioning technology light enough was up to the precision required.
The 90s is another matter. The DC-X was pretty much a direct ancestor of the SpaceX and Blue Origin plans. Still, it would have required a manual or remote control landing, which would be horribly inefficient compared to an entirely computer controlled 'suicide burn' landing. Even so there's a world of difference between being able to do something and actually doing it.
>Compared to what was achieved in the 60s it doesn't seem that impressive.
Is all of computing since 1960 unexciting and pointless? It's just making computers faster and cheaper, so what? The internet? We already had networks, who cares? It turns out that scale matters. Cost matters. Access matters. Details matter. If you can't see the value of treating rockets more like airplanes then you have a small-minded worldview and I don't know what to tell you.
History is littered with inventions that didn't amount to a hill of beans until someone else found a way to turn that invention into an awesome product and sell it to a much wider audience.
When a trip into orbit costs $20,000 then a lot more people can go. When it costs $2,000 then anyone in the developed world can go. What impact that will have on our society?