Everyone is missing the point here. The problem isn't that these cameras are old tech and using outdated CCD censors. If these were the best images we've seen to date of Mars, you're right, there'd be a "Good Enough Factor" — the best images we've seen from a NASA mission, but not as good as modern DSLRs. Understandable.
The problem, that I think a lot of people are missing, is that Viking 1, from 1976, took higher quality pictures of Mars. http://f.cl.ly/items/0k2w2d1C1O3w3e0t300f/NASAQualityDegreda...