This is my James Bond impression.
I've always found it significant that Susan's siblings make no comment on her issues. Peter "shortly and gravely" mentions she's not there, but the overtly critical ones are Eustace, who has a history of bluntness and can likely see some of his own former immaturity in her; Jill, who hardly knows her and never met her before the change; and Polly, who's always been outspoken and may have only recently met her too. No one who's been with her in Narnia. No one close to her as a child. Too painful