[snickms]

What if in the future we could examine the contents of a particular rock from space? Have instruments sensitive enough to detect the remnants of Vogon breath from their visit millions of years ago?

A pristine planet has value beyond 'I want this' IMO - it is an opportunity to perform experiments in an almost perfectly isolated test tube.

As a human, I also find it beautiful. As you say though, this is an anthropocentric view.

[ozim]

Well but it is potential value, what if we never get such sensitive instruments?

I expect Mars to be big enough that when we will have such instruments there still be a lot of stuff not touched to use those on.