The cost of the Space Station relative to the science it has given is obscene. We could have gained this science at a fraction of the cost with unmanned satellites.
It was really all about public prestige. Bring the personnel home and de-orbit the damn thing over the pacific.
No, actually you could not. THE main type of data gained is the long-term effects of weightlessness on the human organism. Only way to get that is to have humans there.