Well, if the truth be told, I reckon "we" would have bogged them in the dust much sooner than actually happened, and "we" would have worn out the wheel motors much more quickly, but 'we" would also have covered a similar amount of ground before they got stuck or broken...

I reckon we'd have done all this inside of 6 months - remember that a lot of the science measurements take time to accumulate the data, so there would be neccesary (and very frustrating) delays to take these measurements - maybe there would have been pressure to take fewer pans and fewer X-ray integrations?

And anyway, the solar arrays/batteries limit available power and hence speed - again frustrating the real-time operations concept (but if it WAS a real-time mission, it would have been designed with more power...)