It's one of my favourite things in a character when they have the virtues of their vices, and this was such a perfect showcase of that: Charles is intensely arrogant about and proud of his superior medical skill - and so when he discovers that his own behaviour is damaging that superior skill, he has to change his behaviour so that he can continue to live up to the standards he sets himself. Love love love it when a story shows a character like that. And Hawkeye's response to it all is so consistent: he knows Charles is very skilled, but he doesn't think it's as impressive as all that because they're all pretty skilled - but he also doesn't think Charles's mistakes are all that horrific either, especially as he's correcting them himself.