Well, there are two different strands at work here- the extreme oeuvre of Bret Easton Ellis (AP being considered by many to be a fantasy or satire; ie was Bateman actually committing murder, or was it all in his head) and the foul behaviour of The Sun and its ilk- echoing the unbelievable targetting of Frank Bruno after his breakdown, and their humiliating and pathetic about-turn later on, ie a feeble attempt to avoid losing 'readers'.
It seems that (surprise!) The Sun never learns, or never really changed. They will begin another witch hunt at the slightest provocation, and their depressing hold on popular culture will continue, and may dictate the views of some of the millions who take in those ill-considered headlines (they claim some balance in the body of the story, but the headlines rather ruin chance of real discussion; in reality, they had muddled the statistics).
So, to address the point, I believe that the appearance of this musical may have less of a negative effect than the Sun's scare-mongering. Culturally, I believe the use of 'psycho' here to be less stigmatising, similarly, Talking Heads and 'Psycho Killer', for instance. The Sun (and others such as Gervais and his cronies) who debase the language in this way currently hold sway in the popular imagination, which is depressing. Hopefully people will lift themselves above this crude and unthinking misuse of English and terminology and grow tired of it.
