After the breakup, Beatles fans expected major statements from the three chief songwriters in the Fab Four. John and George fulfilled those expectations – Lennon with his lacerating, confessional John Lennon/Plastic Ono Band, Harrison with his triple-LP All Things Must Pass – but Paul McCartney certainly didn't, turning toward the modest charms of McCartney, and then crediting his wife Linda as a full-fledged collaborator on its 1971 follow-up, Ram…