Well , I believe that the standards are set by the likes of "The Idols" reality TV programs all over the world and everybody think that is the "sound" that will make it onto becoming world famous or at least famous in their own countries. If you have noticed, there are very little distinction between the winners year after year.
Why does all new pop music sound the same?
Basically because it IS the same - I think anyone with ears already knows that, but there is more to it.
https://www.youtube.com/watch?v=oVME_l4IwII
https://www.youtube.com/watch?v=oVME_l4IwII