As far as I understand there is still some time before humanity becomes interplanetary in any meaningful way, maybe even many generations. And what is going on so far these days is mostly about not regressing.
I doesn't seem clear at this point whether re-usable will be significant for activities beyond earth orbit. Partly the excitement comes from being a workaround for humanities reluctance to spend money on space exploration. Believe what you want, but from what I can find this doesn't seem to be a significant part of what would e.g. make humanity interplanetary. At least not yet.
Getting to orbit is hard, for anything big beyond earth orbit, we'll probably need manufacturing or at least some assembly in orbit. That takes a lot of trips from earth to orbit. Making that more efficient means more resources left for the real exploration.
I dunno if I really follow your logic here. It would be nice if nobody cared about money and we all just worked hard to make everything awesome or whatever. But, we (sadly) don't live in that world. So in this world that we do live in, bringing down the cost of getting things/people from the ground to really really high up in the sky can only be viewed as a step towards becoming multiplanetary.
>I doesn't seem clear at this point whether re-usable will be significant for activities beyond earth orbit.
beside everything else, getting retro-rockets work well at hypersonic speeds is a key to landing on Mars (I really loved the de-facto SpaceX propaganda series "Mars". Even better than "Martian" for me. The only slight disappointment is the cop out at the very end).
My great grandmother was reading a pulp magazine about man going to the moon when she was young, her father made a point to check that she understood that such things were impossible if not extremely far off in the future. The only reason I know this story is that she survived to watch the moon landings and told my father, who told me. The moral of the story was always that it's very hard to predict technological growth, in particular, we tend to undershoot with our long term predictions. Personally I tend to be more weary of people that claim something won't happen in my lifetime than people that tell me something will happen.
By that definition, the Apollo program had reusable rockets. (Able to climb back out of a gravity well, leave orbit of a large mass, and return to earth).
Escape velocity of Mars is less than half Earth's or about double the moon's.
In the past we even had space ships, which could start from ground, go to space, do stuff, come back and the could be reused. Having just a rocket isn't that much of an improvement.
That said: All the constraints on making it reusable and safe for humans are also a key factor why Space Shuttle was so expensive. With SpaceX's rockets not all parts need to resist the stress of reentry etc.
> In the past we even had space ships, which could start from ground, go to space, do stuff, come back and the could be reused
The 're-used' aspect of the Shuttle involved massive re-fits which took months for each vehicle. It was like having to send your car back to the manufacturer for a total rebuild (often including engine change) every time you went for a drive. SpaceX is a massive improvement in this respect.
Nitpick: the boosters were reused by parachute splashdown, but it was also really expensive due to (among other things) the corrosiveness of salt water. The External Tank was in fact expended.
Each SRB consisted of 11 cylindrical steel sections. After flight and recovery, these were dismantled, refilled with solid rocket fuel as appropriate, and then reconnected to form a new SRB with all of the O-rings, etc.
So also a complete rebuild, with reuse occurring at the segment level, not of the whole booster assembly.
For all its faults, and it had a few, Three Body Problem by Cixin Liu helped stretch my perspective to be ok with the fact that space travel could be a multigenerational activity even with a quantum leap in technology.
