Please dont kill me for asking this but why is it that when someone dies everyone pretends they where perfect?

Like for the past ten years Michael Jackson was known as a weirdo who molested children and now that he has died everyone is like "OMG HE DIDNT DO THAT THE MEDIA MADE IT UP?. I mean even if he didn't do it he still has the same allegations as he did before he died, so why is everyone just suddenly changing their mind?