Furthermore, its interior ergonomics are zero-gee too. Under gravity, half of its workstations would be on the ceiling.
Simulated gravity is a good idea, but we would need to start with a blank sheet, not try to adapt the ISS to it.
As for unmanned expendable boosters, there are already many to choose from. Assembly lines are already running for satellite customers, all it would take is a phone call to increase capacity for ISS support.
No argument there. I'm not suggesting spinning ISS around on a line. Rather I think the Spacelab/Mir/ISS concept is already outdated. Perhaps there are some longer term studies that can be done on ISS that can't be done on the shuttle, because the shuttle doesn't have the duration needed. Most of these studies involve the effects of weighlessness on living organisms, which in my opinion is the wrong thing to now be studying. We know that zero gee in the long term is terribly detrimental to human life, and while the effects of zero gee on plants and lower creatures are interesting, of what worth are they when we already know how harmful zero gee is? Perhaps some good will come from plant weightlessness studies, but I think now is the time to start approaching the problem from the other direction: how do we start making artificial gravity to avoid the harmfull effects of weightlessness.
This is not a question that the shuttle or ISS can easily answer. IMO, I think we need to start thinking about those rotating ring stations, heavy lift capacity, and smaller safer manned vehicles.