People who were looking could see Cobain's demise coming. He'd attempted suicide in Italy before the end, IIRC. And he wasn't as big an icon as MM. Diana's death would have been comparable in the UK, IMHO.

Marilyn's death was unexpected and she was a huge icon. I don't think even Judy Garland came close to MM's status (though I wasn't around when JG died).

Cheers,
Scott.