I think the public enjoys these discoveries even if they aren't as drammatic as finding life on Mars.

As for NASA choosing not to send life detection equipment aboard the rovers, that was a scientific decision and not a political one. Afterall, since Viking, we've known that the probabilities for finding evidence of microbial life on the surface is pretty darn low. So why waste time and money tilting at windmills?

If we find microbial life on Mars, it's likely to be beneath the surface. Given that, the only way we're going to find the little buggers is to learn more about the geology at the surface so we know where best to dig.