I think the explanation is satisfactory, but how often, if at all, do other components of such projects change, up until lift off? I imagine engines and other propulsion parts won't be upgraded much after the original spec, even if such components even remotely followed the same curve of improvement as digital chips do. But what about other types of sensors used by the rover? What is the most recent piece of tech used by the rover?

In any case, it's kind of surprising that by 2004, NASA engineers wouldn't have proposed a solution that anticipated vast improvements in digital sensor technology, so that something, in 2009-2010, could be "dropped in" (relatively speaking, not literally) as a replacement.

Of course such a design feature is going to take way more planning and resources than it would for the holiday consumer camera lineup...but a) this is NASA, some of the best of the best engineers. And b) while panning-and-stitching is always a solution, doesn't that have additional operational risk of its own? Additional panning requires additional mechanical movement and attention to moving parts.