um no we wouldn't. How can you justify the statement that we would have interstellar travel by now? We might have a more advanced space program or have found solutions to world hunger, but I don't think we'd be to proxima centauri yet. Besides we do not know enough about the few planets we've found that scientist even think can support life, to know if we could even survive there for sure. At best we might be on Mars.
If all the money this planet has put into war and weapons over the last hundred years or so was taken back and pooled towards technology to make life better for eveybody, we would be on different Planets on a regular basis by now...and technology would adavnce 2 times as fast.
As noble as your notion is though, really as a speicies we will never get along well enough to not need, or want weapons. Besides thing about what this forum is based on, toy guns. Why do we have toy guns? because real guns are cool. Why are real guns cool? Becasue humanity is agressive against itself and idolizes fighting heros who use weapons. It goes all the way back to the cave man days when weapons were needed to hunt so a tribe could survive. The nerf gun is an exention of the early human spear. Spear to bow to gun to nerf. Each associated with heros to build up the coolness factor and interest by a new generation.
Look even at our board. Vacc, Spoon, Stefan, Ash ect are inspirational legends in their own time that create greater interest in the sport. So be thankful we have guns otherwise there would be no nerf, even if a vaction on Mars would be cool too.