But even if we would have frontiers for expansion (the window of opportunity opened once more thanks to Rosetta) we are stuck with a suffering environment, not to mention human suffering.
You'd have to ignore the plight of the Native Americans, for whom the suffering still isn't over but also take into account that as soon as that Western Frontier was closed, the suffering of the rest of the world began (see America's expansion-politics which date in more covert forms back from the early 1800's).
Yes, art, culture, laws have benefited, for a time. But the complexity with which laws for example have formed have nothing to do with justice anymore, only with legality. And right now that means that whoever has the big bucks makes the rules. And the rules are kept in place to profit, which inevitably means there has to be suffering (for without it, many flourishing businesses would cease to exist. THat will vex the companies' respective shareholders).
Art, music, transport, communication: it's no longer about improving the all-over state of the species (which one could state when talking about the old inventions) but to make a fast buck and plenty of them. The idea of programmed obsolescence abhors me to the core.
In other words, what is there to expand TO? We haven't even been able to fix our already existing problems, how would we ever be able to get it right if we were to explore/colonise/utilise other comets or planets? You cannot fix problems using the same attitude and tools which have created the problem in the first place.