I've written about the metric rigidity of pop music before in my post The Tyranny of the Backbeat. To go a bit further, not only is all current pop music in 4/4, but it is rigidly so: the computers run the tempos these days. Interestingly, in the comments to the article several people mentioned some exceptions to the 100% 4/4 and a lot of them were Beatles songs. Well, sure! But if you look at current pop music, not music from forty or fifty years ago, then there are very few exceptions. I am constantly amused at the descriptions of pop music you see, usually by promoters, that wax lyrical about the unique specialness of the artist's emotional commitment or something and then as soon as you hear the song, it is the same old 4/4 backbeat and all too often at exactly 120 on the metronome. Oh yes, terribly unique!
Let's do my YouTube survey of pop music thing, which consists in typing random letters into the YouTube search and seeing what comes up. Here is what comes up with 'a':
Sorry for the juvenile intro, but just listen to the song. Yep, it's three for three: 4/4, backbeat and exactly at 120 bpm (beats per minute, the metronome marking that indicates the tempo).
No messing around there: straight to the drum machine. 4/4... But wait, I detect some innovation here: there is no backbeat as all beats are exactly the same, plus, I think the tempo is the radically different 122 bpm! Go Britney!
The letter 'c' brings us "C'mon" by Ke$ha:
and again, it's three for three: 4/4, backbeat and 120.
Doesn't anyone ever notice the aesthetic dissonance between all these wild and crazy, free-spirited artistic souls who just happen to always follow exactly the same metric formula in their songs?
And speaking of the Beatles and metric variety, the song from the White Album, "Happiness is a Warm Gun" by John Lennon begins in 4/4, but later on is in 5/4, 9/8, 12/8, (and goes back and forth between the last two a few times) then 10/8 in case you were getting bored, 2/4 and finally back to 4/4. Don't ever tell me Ringo didn't earn his money!