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There was a paper I read some years ago about a music student analyzing modern trance music, how it relates to ancient tribal music, and how both relate to the brain. It also explained the mechanism behind the "drop", how the drop is caused by the brain anticipating it and then getting a reward for a good prediction, just like you feel nice when you can predict a twist in a movie or an ad.

What I am saying is that I think that what makes 4/4 so prevalent today is that it is somehow deeply connected to how our brains work, and if you consider popular music subject to Darwinian pressures, it is likely that 4/4 is the most "evolved" one (from a fitness view).

Anyway, I think that in 10 years we will be passing all of our music through a deep neural network, and then ask the network to create new things, like invent a new number one hit, cultural style, or create a new work in the style of Beethoven.