He said that computers have caused this in movies, because now every frame can be manipulated separately.
Art goes through phases - maybe there was that guy back during the Renaissance complaining about how all the sculptures looked the same, etc etc. This is simply the way art goes.
It's like AutoTune in music: people have always tried to sing in tune, but now they can sing even more in tune, and so current pop music has almost lost the naturalism and emotional effects produced by subtle variance in pitch.
We've certainly lost a lot of aesthetics as art styles changed over time - when's the last time you saw a good tapestry? I don't see this as particularly bad, though, it's simply "the way it is" in art. Periodically we will exchange one thing for another, and life goes on.
I agree it can become a bit silly when lots of different singers start sounding alike, but when done well it can really work and have definite effect.