The three laws worked really well as a literary device exactly because they are completely inadequate as an design / engineering / ethical tool. The stories are about the problems caused by the three laws, and how interesting they are. No one who has thought about it a bit, and certainly not Asimov, would seriously recommend them as an engineering solution.
Moreover, he sidestepped misuse of the tech by claiming that the Laws were "hard-wired" into the design of the positronic brain. Not only could be the Laws not be over-written, it was literally impossible in Asimov's universe to create a robot that was without them.
In real life, we know how trivial it would be to completely overwrite the operating system with arbritary software.
