i think it was heath ledgers death that made the movie a hit tbh..
i could not imagine the film with him still being alive, his role was excellent but whats the difference then any other actor playing a madman?
A lot. The synchronicity between his voice, his vocal acting, and his physical acting is rarely achieved in Hollywood, and only by a certain few like Stanley Tucci, Christian Bale, Ben Kingsley, etc. Look back at Ledger's career up to that film and tell me another movie he completely transformed into something that he clearly was not and sold it through an entire film.
We can argue that the film would not have been as popular, and I could agree or argue that theory with you. The bottom line is that people got wrapped up in that Joker character that he created for the film. A lot of non-supporters I'm sure came out because of that whole "freshly dead celeb is in a postmortem-released film", but why didn't Imaginarium of Doctor Parnassus just blow the fuck up out of association to your opinion? It truly was his last film. He died during filming.