Scientists experiment because they don't know the outcome of events until after they've done it. Except by the time they learn it was a mistake, it's already too late, they can't undo it and have let the cat out of the bag. 'Lawnmower Man' was an example of this. The mad sadistic greedy vengeful scientist is one of sci-fi's oldest tropes. GR and Trek shied away from it as he didn't want it or space pirates as standard sci-fi cliches to fall back on. He didn't even want to use Klingons.
He didn't want to use Klingons?????? In TNG initially, but that soon went out the window. That was more TNG standing on its own than anything else. TOS had a few "mad" scientists. Dr. Korby and Dr. Adams come to mind. Then there is Daystrom and good old Janice Lester. As for pirates. Did you notice what Mudd was wearing in "Mudd's Women"?