I didn't even notice this transition.

Over the last several years, pop music has been inundated by massive hits with one-word song titles: “Happy”, “Fancy”, “Rude”, “Problem”, “Jealous”, “Chandelier, “Hello”, and “Sorry” are just a few examples of this trend.

We are in the era of the shrinking pop song title. The transition has taken place slow enough that you may not have noticed, but when you look back at the history of pop, the change is stark.

Just realized Patsy Cline, Willy Nelson and Seal all had a hit song titled Crazy.

And Gnarls Barkley.

And apparently many others: http://www.who-sang-that-song.com/crazy-title-songs.html

That's ... CRAZY!

The theme resonates with a lot of people.

Most people know someone who is crazy.