Frankenstein's Theme of the Consequences of Carelessness and Cruelty

Mary Shelley's Frankenstein overflows with profound themes that force the reader to second-guess the compassion often attributed to humanity. Indeed, one of the major themes of the novel is the inevitable, often terrible, consequence of carelessness and cruelty.

"Life and death appeared to me ideal bounds, which I should first break through, and pour a torrent of light into our dark world. A new species would bless me as its creator and source; many happy and excellent natures would owe their being to me." Doctor Frankenstein, about whom the book mostly revolves, believed these thoughts as a young scientist, dreaming of discovering the means of giving inanimate matter life. No thoughts of the doctor's are spent upon the effects of his future success; he sees no possibility of danger or error. The reader wonders: does the doctor ever consider, while he is making the monster, to make it beautiful instead of ugly? Is he so blinded by the prospect of fame that he fails to notice the need for improvement upon a "sight tremendous and abhorred?"
Merriam Webster defines carelessness as "a free from care; untroubled; indifferent; unconcerned; not taking care." It is quite a pity that the doctor was so utterly unconcerned with consequences that he neglected to construct a creature that would be accepted by the human race. Because as much as we would all love to deny it, humanity is generally incredibly vain. Reading Frankenstein has compelled me to believe that vanity is one of humanity's greatest flaws. Hardly do moderately ugly things (or persons) become accepted; imagine how awful it was for the monster to be considered the most detestable, grotesque creature ever shunned by humanity. His heartbreak must have been unbearable. If Dr. Frankenstein had thought beyond his ambitions of fame and recognition to provide for the life he was creating, the novel's central conflict, that of the monster's unparalleled loneliness because of his appearance, would not have existed.
Cruelty follows the creation of the monster almost immediately, and many may assert that the act of creation was cruel as well., since the monster was created without regard to its future happiness. From the monster's narrative, we learn many of the details of his early life. He learns to adore the DeLacey family; yes, the doctor (and the reader) realizes, this creature has the capacity to love. Yet he is met with extreme cruelty, even from these supposed "best" of people. They enter the house and find him gruesome and threatening, rejecting him violently. Here Shelley makes us wonder whether the monster's later vicious crimes (the murders of William, Clerval, and Elizabeth and the framing of Justine) are somewhat understandable. Murder is never the right option, but after the DeLaceys cast him off as detestable scum, one can only imagine that he will be angry. His anger is justified to many readers, although his outlet for this anger (murder) is not.

So my question to the reader (of Frankenstein and of this humble blog post) is this: are these crimes equally terrible? Carelessness created a monster who was hated by those he loved, as well as his creator. Cruelty fueled the monster's anger towards humanity, and perhaps played a part in his impulsive birth.
What do you think? Comments are welcome!