Not considering rap ('cause it's not worth considering), you wouldn't believe how many pop recordings today are entirely, or almost entirely, "built" with programed samples, loops and plug-ins. They contain no interesting nuances, no personalities, no real life. The stuff pushed by the record companies today is of such simplicity it's insulting. It's no wonder most of the music produced today is discarded tomorrow.
Today's big record companies are not like they were in the 60's. The lack of talent, along with a structured environment that supports the growth and development of artists, are why we have such a homogenized top 50 offering today. I looked at Billboard's top 50 for the week and found 3 artists who I think have been making music for about 10 years, 42 we will likely not hear from again after two years, but most interesting is that there are 5 artists in the top 50 who have been making the charts since the 60's. What does that say about the record companies today and their commitment?
The world population has more than doubled since 1960. No doubt there is more talent available today than there was in the 60's. With twice the talent, twice the consumers, and many times better means of distribution, what would be the reason for declined sales? The problem lies with the record company's desire to get in, get out, and move on. It's a "drive-through" mentality.
People will eat fast-food, not for the enjoyment of the palette, but as a quick filler for the stomach. However, most would select filet mignon over hamburger when given the choice. There is more to it. More smells, flavors and textures, more intrigue and complexity. A bit more left brain fun. The general population would certainly develop more sophisticated tastes in music if given the opportunity, but for now, the record companies are in the fast-food business. They don't like risk and they don't have patience. They like repeating simple, proven recipes that include cliche's, which help to mask the cheapness, much like salt and sugar does for a Big Mac. Forget about interesting melodies, rhythms, harmonies, tones, not to mention humans expressing themselves with physical instruments.
And what about the sound quality of the mediums? Well, it's worthy as a separate topic, but suffice to say, MP3 (1/10th the data of standard CD) heard through ear buds is not very inspiring. Yet this is common place among young people today, while they are multi-tasking!
Generally speaking, the quality of the song writing today is lower, the quality of talent is lower, and the quality of recording process is much lower. Many of the hits today don't even use musicians. Programed music saves a ton of money for the record companies, but at the expense of the soul of the music. We have high quality, extremely affordable digital technologies available to operators who are uneducated regarding best practices.
I believe that if consumers were offered real meat for the same cost as the junk food they are currently being fed, they would discover they like many other foods, which would boost CD sales. People tend to gravitate towards quality, and quality always outlives cheapness.