What do you do with space? We send astronauts there, they do stuff, they come back.... Is it a question of science & technology, or philosophy, whether to send people up there?

I dunno. Most of the assets in space are unmanned: telecom sats, GPS sats, weather sats, telescopes. We're pretty sure we're going to keep up that stuff. They're useful to most of us. Where humans in space are concerned, it's hard to find one thing they've done for people in general, except boost national pride, which in the US is bordering on a superiority complex.

If it were me, I'd be doing life experiments with fast breeding cockroaches in orbit. Changing the conditions in the habitat, seeing if some will survive and breed in increasingly hostile conditions. That sort of thing. Then we'd have some idea of what traits are needed to lower the cost and complexity of living on other worlds.