I think it is fair to suppose that writers and producers are getting better at homogenizing music into what will sell now. I had heard that there were only a few writers who wrote most of today's pop songs. I had no idea it was only two writers until I watched this. Of course everything is going to sound the same when this is the case.
Just like with movies and publishing, the money that finances these enterprises is risk-averse. That's why we end up with Batman Returns Yet Again IV in cinemas and nothing but Tom Clancy's Blah-Blah on airport "book" shop shelves.