Creative reasons for negativity behind 'Rockstar'

OK, admittedly, I haven't actually listened to Rockstar, but history HAS proven that meldings of hip-hop and rock can work. Steven Tyler and Joe Perry definitely did it well with their chorus vocals and guitar on Run-DMC's cover of 'Walk this Way', and who can forget Tyler doing the chorus and Perry playing the guitar coda on Eminem's 'Sing for the Moment' (which actually samples Aerosmith's 'Dream On')? Maybe Brian isn't quite suited to do such a meld.  All the hate for 'Rockstar' could come from the fact that this particular attempt at bridging rap and rock doesn't work.

Whats 'Rockstar'?

My problem is the person he's doing it with...who's effectively a petty criminal who represents what's wrong with a lot of humanity at the moment.

is a whole damn business