Humans have been on the moon, but except for a moment of feeling proud of oneselves, that didn't really earn us more insight than unmanned probes, so it was only plausible that decades went by without further manned visits there.
It won't be any different with Mars. Somebody will go there one day, for earning the fame "to have done it first". He will find the same boring dust there that we already know about. And again, decades will pass that don't see somebody repeat the stunt.
I wished that mankind would invest more into exploring the very interesting places that still remain largely unexplored on earth, like the depths of the oceans. And using unmanned probes is fine there, too, it's just much cheaper and means less unnecessary risk.