Richard Thaler made economics more messy

> Isn’t all this the same thing that Simon got a Nobel for in 1978?

My understanding is, no. Simon's work dealt with microeconomic decisions, which is exactly what Thaler said many were dismissing as self-cancelling noise at the macro level. Kahneman's demonstrates it does not, at least for a subset of macro decisions.

It's because very few of them listened to, or believed in, their psychologist colleagues. And given how difficult it is to conduct experiments at the macroeconomic level, the field as a whole has a poor tradition of running experiments and collecting evidence, which would have burst that bubble decades earlier.

Because "it's complicated" isn't usually considered an exhaustive exploration of the topic?

It's also a great symbol, emphasising how economics is trying to incorporate new knowledge of all the "failure modes" of classical models. There are enough people retelling that "square chicken" joke over and over, and such prices help to spread the word that, contrary to public opinion, there are lots of efforts to make the models match closer with behavioural realities.

Simon was more about decision-making in organizations. But Kahneman certainly did a lot of work in psychology that helped form the basis for behavioral economics work.