I think it's because people saw those simple moral lessons when they were 8, and somehow expect to be challenged to an equal extent as an adult.
TNG wasn't ever particularly profound, it was a popular weekly drama series with plenty of action, adventure and joy.
This season of Picard has captured that quite well overall. There's been some nice themes throughout of loss, grief, parenthood etc. That's about par for Star Trek throughout it's existence.
I feel like the moments between characters have been a whole lot better than the overall plot. But how much of that is me just happy to see the old characters interacting again?