I loved the movie, which came out in 1989 — pre-9/11, pre-Colombine — but quite aside from the whole problem of making movies into Broadway musicals, the theme of a teenage rebel blowing up all the kids at school feels quite different. But The New Yorker says the "issues of bully-related suicide, school shootings, and bomb threats are even more relevant."
"Bully-related suicide" is an interesting expression here. The bullied kids commit murder and disguise it as suicide. It's a dark and comic fantasy of revenge against the bullies, taken to the extreme of a willingness to blow all the other kids away. That's what — post-"Heathers"-the-movie — the Colombine shooters and Adam Lanza did. So the themes from the old movie are "relevant" only in a very distorted way. Where's the comedy now in killing the mean kids at school?
(I suspect The New Yorker writer was writing from a press release and doesn't actually know the movie and what the story really is.)