It isn't a question of sentiment or anything like that--the song has to be catchy--whether the subject is love, murder or mayhem is irrelevant--audiences, for the most part, are pretty much indifferent to emotions, and only respond when the lyric is easier to remember than not--Many pop songs are way over the top because the listeners are so insensitive that that extremes are the only things that get a response. If the mass audience was really sensitive, lyrics would be very subtle--
That said, I have a morbid fascination with songs that are either extreme, trite, or extremely trite. I have Bobby Goldsboro's Greatest Hits, and listen to "Honey" whenever I can--same with "Seasons in the Sun". There are a lot of "folk" songs that resort to extremes, as well, and, at least to me, those are part and parcel of the same thing--
I think that most performers decide early on whether they want to express themselves musically, or whether they want to please an audience (most writers, too)--after that, the road leads you--