Omeprazole has been about for nearly quarter of a century; and is fairly well understood - hell I can walk down to my local drug store and pick up a load from the shelves.

What you are describing, IMO, is either one of two things:

- a systemic failure in healthcare provision (not drug development)

- or a valid trade off between cure and side-effect

If what "advancing knowledge" means to you is "we think we know what's going on and we think we can do it better next time,"

The problem here is that you're going to kill a larger number of people in-trial due to mistakes or missteps. We know this because that is what early medicine did. Whether this is more than those who would die without aggressive research is something of a moot argument. Arguing the numbers is largely pointless because it's impossible to predict what will happen (that, after all, is the point).

Now; I see your argument that this is a valid tradeoff. Indeed, I think we should take more risks than we do. But not quite to the extent you are arguing.