This is all true, and is all well and good for unmanned space exploration (yes, getting to LEO is halfway to anywhere), but for manned spaceflight time is also

This is all true, and is all well and good for unmanned space exploration (yes, getting to LEO is halfway to anywhere), but for manned spaceflight time is also expensive - every day spent in flight adds mass for life support and supplies, and also increases the human risk of a failure. For yet more perspective - an astronaut on the ISS in LEO is at most a couple of hours from the ground-based facilities in an emergency, probably more accessible than researchers at the South Pole. Sending people to Mars (on the order of magnitude of a year round trip, with very limited opportunities for early return) would require them to carry with them not only more expensive redundant systems, but also more advanced medical equipment and repair systems than anyone has had to carry into space before (which requires yet more mass, and hence a bigger and better launcher). Of course, Orion itself doesn't deal with any of these issues - it's meant to be used for ascent and Earth return only, and to be attached to the larger systems that deal with the challenges of a Mars journey. Which indicates pretty well how little of the engineering work has been done towards NASA's Mars mission.