I would not say TNG was particularly more subtle. A gendered alien from a genderless race being put through conversion therapy is about as subtle as Let That Be Your Last Battlefield was. A planet of literal Native Americans in space being forcibly moved by Picard, who finds out he is the actual descendent of a 17th century coloniser, is somehow even less subtle. The Measure of a Man would have worked without explicitly bringing up slavery, but they made sure that it was brought up, and that it was a black woman who did it. Star Trek has pretty much always shouted its message for the people in the back row.
I would not say TNG was particularly more subtle. A gendered alien from a genderless race being put through conversion therapy is about as subtle as Let That Be Your Last Battlefield was. A planet of literal Native Americans in space being forcibly moved by Picard, who finds out he is the actual descendent of a 17th century coloniser, is somehow even less subtle. The Measure of a Man would have worked without explicitly bringing up slavery, but they made sure that it was brought up, and that it was a black woman who did it. Star Trek has pretty much always shouted its message for the people in the back row.