I think that's an excessively intentionalist view of evolution. Evolution doesn't test the waters, in the sense that it inhibits a harmful mutation from happeni

I think that's an excessively intentionalist view of evolution. Evolution doesn't test the waters, in the sense that it inhibits a harmful mutation from happening again, nor are mutations likely to be purely good or bad; mutations are random changes, and are (definitionally) more likely to be passed on if they increase reproductive fitness, and that's about it.