I am actually more annoyed at Chopper, he had absolutely no big moment or character development ever since the timeskip. He's just a miracle healing device, who should honestly struggle more at healing and finding cures, and had been challenged in his dream and beliefs at least once until his finds his strength back and finds a compromise.
Big Mom's illness could have been an opportunity for Chopper to shine and get some development and struggle, with him getting an interest upon learning of Big Mom's unique illness and struggling between being terrified of Big Mom and knowing she's a terrible enemy, and his doctor conscience telling him that he should try to find a cure or treatment to her sickness and him struggling to find a cure or treatment to it before having an eureka moment and finding a new medicine or vision and treatment in the domain of mental health, with him serving as the peacemaker between the Straw Hats and BMP as a result.