Ten years ago, I wrote an article on the history of robotic Mars exploration which was published in the October, 1989 issue of the EJASA and the August, 1990 issue of Spaceflight.
You can read the EJASA article here:
I wrote the article in response to the then recent failures of the Soviet Phobos 1 and 2 probes. One thing you will see is that failed Mars missions are not uncommon. Ironically, the Soviets have had better luck landing on the surface of Venus than they ever did on Mars.
I take it as part of the price to pay to explore space and the fact that sending probes to other worlds is still far from routine.