Really I think every director goes through that though. Every director films FAR more material than they KNOW will fit into a 2 plus hour movie. Coogler I'm sure knew darn well that the Black Panther movie wasn't going to be 4 hours long. Obviously you have to cut stuff, and it falls on the director to cut and edit the material into a movie that works.
And it DID. Honestly I'm a little surprised that there is as much criticism as there is for the fighting in this movie. As far as fight scenes go in the MCU, I think it's at least gotta be in top 5.