It's his home movies with Love and baby — some playful, others drugged and drooling — that fans will find the most emotional viewing. As the credits roll, it’s hard not to just root for the sensitive, progressive, fiercely creative Cobain and wish that he’d lived long enough to find a little peace of mind. Mr. Morgen was given access to Cobain’s archives — “art, music, journals, Super 8 films and audio montages” — and his exhilarating, exhausting, two-hour-plus film, both an artful mosaic…