Do you really expect Universal to design a park with a whole land presented in a way that precludes kids (and therefore, families with kids)? No, really. Are you expecting the Monsters to be a scarezone from open to close? Because that would be remarkably short-sighted.
And that touches on why I think a family coaster here is a much better investment than a show. Basically, there needs to be something that visually attracts kids to that area of the park. A “monster ride” implies scary. A “monsters show” implies not kid-suitable. An outdoor family coaster is far less questionable for everyone in a nothing else would be outside a flat spinner. That’s why I’ve been such a big advocate for Scooby Doo’s Spooky Carnival as a Monster’s mini-land.
I also think a coaster adds some kinetics to the land which was sorely lacking compared to the other lands. Nintendo and Dragons are notably “busy,” but even the Ministries will likely have a lot of “movement” with projections and screens. Monsters had none of that.