"Had I approached my discovery in a more noble spirit, had I risked the experiment while under the empire of generous or pious aspirations, all must have been otherwise, and from these agonies of death and birth, I had come forth an angel instead of a fiend."
What would Jekyll have done differently under nobler intentions? He would have attempted both of the goals he began with:
"If each [side], I told myself, could be housed in separate identities, life would be relieved of all that was unbearable; the unjust might go his way, delivered from the aspirations and remorse of his more upright twin; and the just could walk steadfastly and securely on his upward path, doing the good things in which he found his pleasure, and no longer exposed to disgrace and penitence by the hands of this extraneous evil."
Jekyll succeeded in his first goal: silencing the "just" superego so that the "unjust" id could do what it wanted with no remorse. But he never mentions even attempting his supposed second goal: silencing the id so that the superego is "no longer exposed to disgrace and penitence by the hands of this extraneous evil." No doubt, had he attempted such a thing, he would have found it completely impossible to suppress evil as easily as his drugs could release it, but he apparently never pursued such a route. Why? Because Evil Feels Good, and he was content to use his first discovery to let himself savor the joys of depravity with no remorse or risk of discovery.
Had Henry Jekyll admitted this in his explanation, of course, he wouldn't be the Hypocrite Stevenson so rightly declared he was.