This is going to be a weird theory but f**k it, here goes:
I think the reason why singing is so popular now instead of actual musician skills, is that pagan magic is being pushed as a new religion. The voice used to be thought to be able to cast spells/incantations, and to the "elite/illuminati/shadow government" tht pushes that agenda there is power in the voice. We also had Skyrim released a few years ago that centered on the theme of the Thu'um(voice). We all have seen in almost every cartoon the use of the words abracadabra and open sesame as well as a prevalence in overall magic and monsters. A common myth about magic was that a wizard/witch could conjure demons/monsters with their words. Magic the Gathering made that apart of their game back in the 90's as well with summons and instants, etc. And speaking in tongues is considered by some religions to be lesser magic as well, but has seen over the last few years a sort of resurgence amongst certain religious communities. I know this is all my opinion(not to mention how it sounds crazy), but I kind of see that being why people like Miley Cyrus, Nikki Minaj, and other singers are promoted so much as well as reality shows about singing competition. Just a theory... :l