Making someone think they're an accomplice to torture is itself recognized as a form of psychological torture. Telling someone that they're helping to advance science proves nothing, except that people can be deceived, manipulated, and exploited by bad actors.

Milgram decided to repeat his gross ethical violation 30 times(!), with dozens of test subjects each time. Overall, the majority of people actually disobeyed the orders to continue with higher voltages.

I think the only reason it's become so popular is because it makes for a shocking story, with grandiose implications. The specific "agentic state theory" Milgram invented is not backed up by his data, and personally, I find it philosophically dubious and psychologically concerning that he gravitated to it.

See:

https://www.bps.org.uk/psychologist/why-almost-everything-yo...

https://journals.sagepub.com/doi/abs/10.1177/095935431560539...