Dr. Jekyll is like, the definition of mad scientist. He started with a hypothesis, one which very few would ever come up with and none other would dare to test: that Good and Evil can be mechanically separated in a person. He devised an experiment by which to put his theory to the test. He used himself as the test subject because crazy, and also because it put him in the best position to observe and record the results. And when things started to go wrong, he not only cleaned up after himself but left behind his conclusions on how and why he got the results he did, for future generations.
Yes, the experiment claimed the lives of several people including himself. Yes, his safety protocols were inadequate and his sample sizes were small. But unlike your garden variety mad engineers and unhinged tinkers, he was a goddamn Scientist.