In past you had to have musical talent to become a musician. People would come to watch the artist create the music.
Today the only requirement is a pretty face, or slick image. The studio could make my cat a rockstar.
Because of that many 'live' shows are now pre-recorded, or just shit.
Great musicians busk for coins in the subway, while untalented hacks, with big racks, collect all the rewards from media.
I know what you're getting at, but remember there's a difference between a musician and and an entertainer. We could discuss the subject for a long time, but allow me to point out just a few to exemplify what I mean.
JJ Cale: Though he deliberately avoided the limelight his influence as a musical artist has been widely acknowledged by figures such as Neil Young and Eric Clapton, who described him as "one of the most important artists in the history of rock". "After Midnight", "Cocaine", "Call Me the Breeze", "I Got The Same Old Blues" to name a few.
Miley Cyrus: Tried to ride the coattails of her father and her TV show, a great example of the Pop-as-a-product record company focus-group management devoted entirely to profit. With much less talent, they tried to update the Madonna style of shock and lewdness as an asset.
Two of the extremes, what about the middle ground? One example might be Steven Tyler. An extremely accomplished vocalist, he puts on one hell of a live show. Mugging and flamboyant in concert, he still had the talent to listen to. Or how about ZZ Top. I remember seeing their Antenna tour. They played their music expertly as always but were almost motionless on stage, depending on a large backlit screen with a scantily-clad girl dancing. Great music but largely unentertaining (to me). Also Eric Clapton. Saw him about 2 years ago. He clearly was just calling it in, maybe just for the money. No audience contact. Sat through most of his concert playing the required hits, very little interaction with the audience or the other musicians. Not very entertaining but musically superb.
Remember, I'm not discussing these particular artists as their abilities/talents or even the single concerts. I'm just expanding on what you brought up by the topic.