I have asked this question myself and it has been asked ofme. I should point out that in all fairness there has probably not been a time in history when absolutely all music sucked. That being said, some eras tend to have an overabundance of good music while others have relatively dry periods. I guess you could compare it to wine vintages (yes, I know that is nota very scientific comparison but what the hey?).
I first tried to check my bias by seeing if this phenomena could be explained by my preference for music that I first heard when I was twelve years old. For more on this see this article: http://www.slate.com/articles/health_and_science/science/2014/08/musical_nostalgia_the_psychology_and_neuroscience_for_song_preference_and.html
This wasn’t true in my case. I found that when I was 12 I had a very broad and eclectic musical taste, since I had older siblings who listened to music and I was very precocious. Nevertheless, there were musical forms that I wasn’t attracted to as a 12 yr. old, such as acoustic Prewar blues, that I really enjoy now. And even though I had had some limited exposure to jazz, it was not until I was older that I really appreciated the art form. Moreover, I know people older than myself who positively worship punk rock, new wave, and rap and they could never have heard these for the first time in their teens.
What is music anyway? It is a combination of melody, harmony, rhythm, and personality. The first three elements can be analyzed logically, but the third element is very subjective and can sometimes trump the first three. When we are talking about recorded music we could also include the aspect of production values. In my opinion, modern music puts a premium on production values to the exclusion of the other elements of music.
From early folk and blues to early New Orleans rock and roll direct to disc technologies were employed such that production values relied on capturing a great live performance. This sense of urgency forced the performers to give their all to the recording. This paradigm has been greatly reversed in recent times.
Personality is largely missing in contemporary performers. This aspect is very much controlled by expectations of focus groups and marketing departments. This is why there is so much homogeneity within genres. There is also no sense of urgency since” everything can be fixed in the mix”.
In the 1960’s and early 1970’s the record companies were run by cigar chomping old white men who (according to Frank Zappa) would say ‘I don’t know if it will sell, but what the hell?’ and so, we were blessed with experimental musical forms. However, this circumstance soon gave way to hip young white guys who thought that they knew exactly what the kids wanted. These execs decided to give us safe choices rather than creative ones and this is how we ended up with what we have today. Just as in movies and television, in the music business, imitation is the sincerest form of flattery.