I've been a musician for fifty years. I see human music as clinging to tiny islands in the sea of possibilities.
One day in Oregon I visited a wildlife reserve for migrating birds. The music of blackbirds is most impressive. It isn't a repetitive song, they improvise. They work off one another's song. They don't use human scales or rhythms at all. It is a completely different approach, and to me it sounds great.
So why is contemporary pop music bad? It has nothing to do with the possibilities being exhausted. The laws of combinatorics being what they are, that will never happen. Indeed mostly I listen to 21st century music. But NOT what comes over the radio. Through modern technology I can hear the whole world's music, even what Chinese teenagers are doing in their bedrooms. There is more great music going on than ever before. There are very talented people who don't want the hard life of a pro musician. Now they can play in the bedroom and make their money by endorsing musical instruments.
Western-style classical music is also coming out of the 20th century atonal dead end. I have heard fantastic wild new "classical" stuff at the arts college in Tokyo.
So why isn't it on mass media? It's because in the 1970's music companies did scientific studies of the preferences of ordinary people. They found that ordinary people preferred very simple music. Ordinary people don't sit down and listen to music. They don't give it their full attention. They give it hardly any attention at all. It's "the soundtrack of your life," something that sets a mood but is not a distraction, that does not draw the attention. They prefer routine, uninteresting, unemotional music. It worked: the market for music is bigger than ever. That's fine with me as long as I don't have to listen to it. They also learned that for stardom music hardly matters at all, looks is what does it. The visual sense completely dominates the aural. Good music for your video is a distraction, a drawback, a cost center, a liability.
Artists from the 1960's are selling more today than they did then! So why go to the risk and expense of developing new musical acts? It's a lot more profitable to sell the old stuff.
I have been in Japan for over a year and the musical environment is completely different than in the USA. Simple music is never heard. The background music in supermarkets and restaurants is sometimes so good I stop everything and record it. Musical performances in Tokyo might be the best in the world. It's because it is routine for kids to learn music starting at age three then practice diligently. There are little piano schools everywhere. I have heard middle school bands that were as good as music college bands in the US. This is normal. So there is a pool of millions of highly skilled musicians. Those who turn pro are the cream of this crop. They are at a level of skill that in the West is unthinkable. They have an audience of those millions of skilled musicians, so they can make a living. Another thing: they learn to actually play the stuff, not rely on Pro Tools to fake a recording. Japanese bands are starting to find a well-deserved audience in the West. They have so much skill that they are overcoming the formidable language barrier.
There is plenty of great and original music being played. But you have to go to it. It won't come to you unbidden. When I was in the US there was a summer series of ten concerts in the park. Nine of them were "tribute" bands, whose goal is to copy an act from the past. In Japan there are very few tribute bands. People want new things.
I DID hear some good original music in the USA at festivals and anime conventions. It's still around. But those acts don't make the big time any more. I suppose they have day jobs.