"It's a huge disaster, but what is the fallout?" asks one source after the sequel to the $1 billion hit bombs at the box office and is rejected by critics and audiences alike.
Same. It's not a bad film. It is a fairly logical progression from the first movie. I was actually surprised it wasn't more fantastical. There were several points where they could have escalated to a city wide musical caper, but they kept it grounded.
Trying to explain why people are breaking into song doesn't ground it any more, and trying to make it "realistic" singing such as part of a stage show or rehearsals just weakens the strengths of the genre.