Why do we need humans in space if we don't need them on the sea floor?

Put these two together:

Kosmas and Posey Urge House Committee to Restore Human Spaceflight Funding


Nereus Soars to the Ocean's Deepest Trench: New hybrid deep-sea vehicle descends 6.8 miles in the Challenger Deep

If robot manipulators capable of doing dangerous work in the deep-sea without humans being right there to be "hands-on", do we really need humans in space?

Now, there is some argument for the human factor. Spirit is currently stuck to its hubcaps on Mars -- a human could have sidestepped the sand trap or more likely realized that it wasn't a good place to step, OR easily devise many different ways to extricate oneself. Plus, Spirit's power budget problems could have been easily fixed with a lightly-applied whisk broom. Nereus is connected to the surface by a hair-thin fiber-optic cable, which I would think is likely snappable unless care is constantly paid. Plus, on the ISS, a bank of experiments might need human supervision; but computer-coupled robots are routinely doing hundreds of biochemical experiments and tests in labs around the world without much human supervision.

Still, the costs of keeping humans in space, particularly the logistics, are so high that I'd like to see the budget numbers on intelligent robots to find out where break-even is. Part of the problem is that NASA is so cutting-edge that they keep trying to be more sophisticated and more complicated, when in some cases just making copies of what works would be VERY sufficient. (As well as cost-effective.) Where's Danny Goldin when you need his advice?

MORE:

Funding threatens US return to moon by 2020: lawmaker [Senator Bill Nelson]