How would you oppose the pessimism of science in Robert Louis Stevenson's Dr. Jekyll and Mr. Hyde and Nathaniel Hawthorne's "The Birthmark"?

Nineteenth-century literature is replete with depictions of scientific experiments and prophesies of new inventions and discoveries. Given that this was an era, like our own digital age, in which the world was being transformed by technology, this particular obsession of writers was only natural. While much of their fiction portrays negative and tragic results of scientific research, it's generally not science itself that is criticized but rather man's own inherent weaknesses and moral failings.
Hawthorne's "The Birthmark" is a parable of man's inability to accept imperfection as an inevitable part of life. Aylmer is a brilliant researcher who has created (interestingly enough, in the previous century, where Hawthorne sets the tale) fantastic inventions which, if used correctly, could benefit mankind immeasurably—just as the actual inventions of Hawthorne's lifetime, such as the telegraph, gas lighting, and railway travel, were doing in a way that understandably was seen as spectacular during those years. But Aylmer, in his obsession with Georgiana's "flaw," misuses the power he has created in the laboratory. This is not the fault of "science" or even of Aylmer's scientific activities, but of his failure as a man in refusing to value his wife as she is, and for what she is, instead focusing on the birthmark which doesn't bother anybody else, including Aylmer's "uncouth" lab assistant. As in other works, Hawthorne is also criticizing the mindset that creates a dichotomy between the spiritual and the physical. Aylmer's unrealistic attitude, including the rarefied way he speaks and the horror he begins to feel when looking at his wife's face, is basically one of disgust with the physical world. Like Mr. Hooper in "The Minister's Black Veil," who cuts himself off from life by covering his face, Aylmer seeks purity but ends up destroying Georgiana and himself.
Stevenson's famous story is a parable as well, in which a man splits himself into two beings. It would be simplistic to give the usual interpretation that Jekyll represents good and Hyde evil. As with Aylmer, Jekyll's brilliance as a researcher is beyond question. But his flaw, again, is the non-acceptance of the real world and a misguided striving for something beyond it, which he believes science can produce for him. The descriptions of his pathetic attempts again and again to find the right formula to restore him to normalcy are a metaphor of man's having succumbed to his own weaknesses and his inability to restore the real but imperfect self with which he should have been satisfied.
Both Hawthorne and Stevenson, by showing hypothetical scenarios in which science can produce results no one could have dreamed of, are actually showing their faith in man's ability to advance. It is not science per se, but its misuse due to human failure that is at fault and that brings on the catastrophe in each of these stories.