I'm not arguing that one side outweighs the other -- adding up all the positives and negatives of nuclear technology would be a significant undertaking -- I'm simply saying that the researchers at Los Alamos didn't fully understand the ramifications of what they were creating, and it was potentially the case that the negatives would far outweigh the positive. One example is that so far we have managed to avoid global nuclear war. But no one could have predicted in 1945 what the likelihood of us avoiding it were.
Similarly with this technology: no one can predict whether this will be a mix of positive and negative, or overwhelmingly one or the other. That's true of most technologies, but to be clear, this is not the invention of Post-It Notes. It is absolutely the case that technology like this could fundamentally change the course of human history -- for good or bad.
And I'm not saying we should try to shove it back in the box. I'd be curious if that has ever worked. Nuclear, sort of? South Africa gave it up, after all. But to do that here would be futile and I'm confident actually push toward negative outcomes.
All I'm saying is that we should be cautious in our approach, not that we shouldn't proceed. In other words, I think "... we can't hold back as a species just because there are drawbacks. we need to build around them." -- we're in agreement :-)