Why are great artists today so undervalued?

I've seen some paintings done by some people on the ABC channel and some of them are fantastic. They match the realism and authenticity of some of the great artists of the past. I dare say that many are even better than what Pico did. There are also great film composers who's compositions are as great as those written by the old composers of the past but they're hardly recognized. What's going on? Even at school and uni whenever a lecturer or a teacher mentions an artist or composer it's always someone who's long gone.