Despite the astounding sucess of the rovers they have done squat compared to what a field geologist could have done in the same time. You pay a lot more you get a lot more. Core drilling alone would be huge. The ability to reconfigure instruments would be huge. The ability to glance around and change directions in the blink of an eye would be huge. The ability to repair instruments would be huge. There are vast advantages in humans over robots for nonroutine tasks. That's why most people in the US and other developed countries are still employed despite modern robotics and their human techs who maintain them on Earth.

The radiation hazard is equivalent to a 2% increase in cancer risk based on total expected radiation dose, about 1/10 th the amount smokers voluntarily take. That's without any additional shielding technology beyond what we've already developed. There are many astronauts willing to take that relatively low risk. This is hugely over blown risk like many others associated with going to Mars. The cure for irrational fears such as yours is educating yourself on the issue.

see ya