For things like vaccines and antibiotics it seems much more likely that we use narrow AI that it is good at predicting the behavior of chemicals in the human body, I don't think anybody is really worried about that kind of AI.
If you actually mean convincing an AGI to do medical research for us, what is your evidence that this will happen? There are many possible things an AGI could do, some good, some bad. I do not see that you are in any better position to argue that it will do good things but not bad things as compared to someone arguing that it might do bad things, quite to the contrary.
And you repeatedly make the argument that we first experienced trouble and then became more cautious. This are two positions, two mentalities, and neither is wrong in general, they just have different preferences. You can go fast and clean up after you ran into trouble, you can go slow and avoid trouble to begin with. Neither is wrong, one might be more appropriate in one situation, the other in another situation.
You can not just dismiss going fast as you can not just dismiss going slow, you have to make an careful argument about potential risks and rewards. And the people that are worried about AI safety make this argument, they don't deny that there might be huge benefits but they demonstrate the risks. They are also not pulling their arguments out of thin air, we have experience with goal functions going wrong leading to undesired behavior.