I think that's overselling the ISS a bit. Humans survive in zero gravity in 2000 - 2016 the same way they did in 1969.

At the risk of quoting all of this essay - http://idlewords.com/2005/08/a_rocket_to_nowhere.htm - from 2005, when the shuttle still flew:

At the now-usual cost of around a billion dollars , STS-95 spent ten days engaged in the following experiments: see how microgravity would affect cockroach growth, Studied a "space rose" to see what kinds of essential oils it would produce, at the suggestion of elementary school children, monitored everyday objects such as soap, crayons, and string to see whether their inertial mass would change in a weightless environment. Preliminary results suggest that Newton was right. Monitored the growth of fish eggs and rice plants in space, checked to see whether melatonin would make the crew sleepy (it did not)

Along with these craggy summits of basic research, the astronauts performed a raft of prepared experiments in metallurgy, medicine, fluid mechanics, embryology, and solar wind detection, all of which had one thing in common - they were designed to minimize crew interaction, in most cases requiring the astronauts to do little more than flip a switch (NASA policy requires that experiments on manned missions involve the crew)

Over the past three years, while the manned program has been firing styrofoam out of cannons on the ground, unmanned NASA and ESA programs have been putting landers on Titan, shooting chunks of metal into an inbound comet, driving rovers around Mars and continuing to gather a variety of priceless observations from the many active unmanned orbital telescopes and space probes sprinkled through the Solar System. At the same time, the skeleton crew on the ISS has been fixing toilets, debugging laptops, changing batteries, and speaking to the occasional elementary school over ham radio

The NASA obsession with elementary and middle school participation in space flight is curious, and demonstrates how low a status actual in-flight science has compared with orbital public relations. You are not likely to hear of CERN physicists colliding tin atoms sent to them by a primary school in Toulouse, or the Hubble space being turned around to point at waving middle schoolers on a playground in Texas, yet even the minimal two-man ISS crew - one short of the stated minimum needed to run the station - regularly takes time to talk to schoolchildren

This brings up a delicate point about justifying manned missions with science. In order to make any straight-faced claims about being cost effective, you have to cart an awful lot of science with you into orbit, which in turns means you need to make the experiments as easy to operate as possible. But if the experiments are all automated, you remove the rationale for sending a manned mission in the first place. Apart from question-begging experiments on the physiology of space flight, there is little you can do to resolve this dilemma. In essence, each 'pure science' Shuttle science mission consists of several dozen automated experiments alongside an enormous, irrelevant, repeated experiment in keeping a group of primates alive and healthy outside the atmosphere.

The science which was advanced, effective, worth doing, could have been done more cheaply with unmanned launches of automated experiments and no ISS.

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NASA dismisses such helpful suggetions as unworthy of its mission of 'exploration' [..] Of course, the great explorers of the 1500's did not sail endlessly back and forth a hundred miles off the coast of Portugal, [..] The interesting bits in space are all much further away, and we have not paid them a visit since 1972. In fact, despite an ambitious "Vision for Space Exploration", there seems to be no mandate or interest in pursuing this kind of exploration, and all the significant deadlines are pushed comfortably past the tenure of incumbent politicians.

The goal cannot be to have a safe space program - rocket science is going to remain difficult and risky. But we have the right to demand that the space program have some purpose beyond trying to keep its participants alive.

Your casual mention of 'ongoing exploration of space' is deceptive because manned missions to the ISS aren't part of the ongoing exploration of space, by virtue of them not doing any actual exploring.