Those mars rovers have been celebrated for their longevity and endurance, and sol they should be. They've been up there several years now, despite their initial mission being expected to last just a few months. However, in all that time they've covered about 8 miles (I think? Couldn't find the exact figure) in a near-straight line and done about three bits of science a day on average. A human team could cover that much distance in a *week*, and could have performed all the science of those rovers plus a hell of a lot more in that time. Humans can make on-the-spot decisions that rover operates at a distance can't necessarily make. Our brains are highly advanced pattern-recognition devices that would be able to spot things in person that even a bloke looking at the camera images from a rover wouldn't spot, and in fact those images are often going to confuse because they lack context. Remember the big furore over that guy who reckoned a picture showed pools of water? And how it turned out to be flat stone on a slope? Context, you see...

That's why humans need to be out there. We're simply better at it than even the most advanced robot.