In the first two movies of Nolan's trilogy, fear has always been detrimental to the one experiencing it. The entire first film was Bruce overcoming his fear and as a consequence becoming stronger and able to overcome Scarecrow. Then the second film dealt with fear indirectly with the Joker inciting panic and terror into Gotham through terrorism. And in all films, Batman literally terrorizes criminals into not being able to coherently fight or conduct business.
It could basically be said that Batman's "superpower" boils down to him overcoming his fear and using it against others.
For reasons I don't entirely understand, though, fear is switched around to being a good thing in TDKR. As in, Batman fails to punch Bain good because he wasn't scared of dying, he fails to jump out of a pit because he's not scared of dying, then the third act of the movie is built around Batman literally jumping and punching better by being scared of dying.
I don't entirely understand where this mindset is coming from. Fear obviously didn't make any of the inmates better at fighting in Batman Begins, nor did it focus Gotham in The Dark Knight. Following the third movie's logic, Batman should have been an incredible fighter under Scarecrow's fear gas and the training montage with Ras encouraging Batman to overcome his fear wouldn't make sense.
Why the switch?