The Hulk's anger was far more of a liability than a help in almost all contexts.
In The Incredible Hulk it's mentioned that the Hulk killed at least six innocent people while on the run, including two scientists, an army officer, a police officer, and a couple of hunters who shot at him.
In The Avengers a minor bit of mental manipulation from Loki's scepter causes the Hulk to run out of control, nearly killing Black Widow, fighting with Thor, causing significant damage to the S.H.I.E.L.D. helicarrier, and almost killing some poor fighter pilot to boot.
In Avengers: Age of Ultron a minor bit of mental manipulation from Scarlet Witch caused the Hulk to rampage through Johannesburg, South Africa, causing millions, if not billions, of dollars worth of property damage and only avoiding horrific civilian casualties through the intervention of Iron Man and a massive amount of sheer luck.
Even after gaining some measure of control over himself and even when not under mind control, the Hulk's anger still caused him to lash out at his own allies (punching Thor during the Battle of New York), require significant handling (Black Widow needing to calm him down after they fought HYDRA), act petulantly and unpredictably (refusing to help Thor on Sakaar), and create many, many problems.
Additionally, it's not clear that the new and improved version of the Hulk is actually weaker than the rage-filled monster that he once was. While he does not contribute significantly to the final battle during Avengers: Endgame, this largely seems to be due to the injuries he sustained using the Infinity Stones rather than a lack of anger.