If John was in love with Yoko and wanted to write songs about her, what's the problem? One can buy or discard his records, it's his art after all and he could do what he wanted to do. I never cared about Yoko's art, but that doesn't define her as a person. What was her sin? Making John fall in love with her? And John wasn't perfect, is that a sin? At least John brought joy to the heart of many people, that doesn't make him a saint, but he was blessed with a gift and used it better than anybody.