All valid reasons indeed.
I believe we know from previous encounters that there is life out there! That alone is a pretty good reason to want to escape the bounds of our solar system and go deep space, but WHY do it when we know that we LACK the technology to travel fast enough to go anywhere in a dozen life times in deep space?
I have read Sci-Fi books my whole life, only graduating to modern detective and forensic pathology audiobooks in recent years. In all my thousands of books a common theme always stood out - somewhere out there is HOME, not where we live now, but where we came from long before we developed into humans and further back before we even crawled on this planet.
It is not exploration that we seek... it is MIGRATION. It is primal and so primative that we have it in our every cell. Many scientist (of the "out-there" type) believe we were seeded from Mars before it died and great ships of Martians traveled deep space looking for a more habitable planet than Earth, which surely wasn't Bio-friendly to Martians several million years ago. But simple life could survive, so such life was sent to Earth as they left for places deep in space.
One can only think that a society, likely a group of countries like ours, but with a unique Martian twist (maybe they we true social creatures, working for a common good at all times) and not just a handful of relatively technological countries willing to shell out big bucks to have a section on a International Space Station that only orbits at about 180 miles above the Earth.
Surely, the Moon landings and safe returns were physical man's greatest accomplishments - I am still always amazed at how they could redock from blasting off the Moon to connecting with the Orbitor and then making it home, spectacular indeed. But we have ventured to Mars with rovers that have worked for years and years after their life expectancy was surpassed. We have lauched information gathering satalites that have left our solar system and will someday die from lack of enery from solar panels yielding energy from our own sun.
Japan has mapped the Moon in such Hi-Def detail that 3D fly overs of EVERY INCH can be simulated with unimaginable resolution. But all of this means little when it comes to seeing our own Milky Way Gallaxy, with its hundred BILLION stars and countless planets, all to far away to ever visit with todays limited technology.
In any book I've read, ships launched 50 years earlier were phyically passed in space by ships launched 50 years later and those passed by ones 10 years after that. Keeping the idea of computer processor growth speed in the late 1990s, we saw doubling of speed, all most exponentially, only to slow down because we had little need for anything faster, nor the means to progress at faster speeds through engineering.
That is the problem with space. We attempt miraculous things and succeed at them, but in the grand scheme of things, they are drops in the bucket of where we might be some day.
I think instead of wasting money building ships that travel to Mars, which we know very intimately through years of data collection, we instead start researching the future of deep space travel - get it working on paper first, not build a thousand prototypes that are just slight upgrades of previous flawed versions.
So, we have been to the Moon, and thinking it happened 40 years ago using less technology aboard the ships than the typical cellphone, it was breath-taking to witness. I have been to the National Air and Space Museum many many times and marvel at the Gemini and Apollo return capsules, the great Saturn Rockets that took us there and everything that lead us from standing on the ground looking up, to seeing the Earth in its many phases, as we see the moon during its 28 day cycle.
None of us alive today will see deep space travel, except through the eyes of Hubble and its improvements (which I haven't heard much about - hummm?) but someday, if man doesn't blow itself up in the process, or over populate ntil all live starves, or natural disaster from space or viral, we will step on the surface of a planet deeper into the Milky Way and thus set another milestone for man, but it will not stop us from going further - we are voyagers, migrators, adventurers, we are humans and at least in this part of space - unique indeed.