Why does all new pop music sound the same?

Generally speaking, talking about modern cables is more interesting than talking about modern music. But there are exceptions. Listen to some Mongolian rock and rap music, as an example.
Also, just because someone is old doesn't mean he is rigid and sclerotic. In fact, I find most younger people incredibly stupid ignorant and underdeveloped. Generation of digital imbeciles. But not all of them, thank you.

After further deliberation on the subject, I think my final thought on this (and that's only because I don't feel like thinking about it anymore) is that, IMO, the "top 40" of the 60s and 70's was more varied in nature than the current music being played on stations like WKTU, which I listen to a lot more than I want to for reasons that have no relevance to this discussion.  Time marches on, music marches on - sometimes for the better, sometimes not.  Peace to all.  

chayro

... IMO, the "top 40" of the 60s and 70's was more varied in nature than the current music being played on stations like WKTU, which I listen to ...

That's certainly true, but it reflects the changes in radio broadcasting and corporate ownership as much as the change in popular music.

Because the ownership caps on radio stations were lifted - allowing giants such as iHeart (Clear Channel), Cumulus and Citadel to own hundreds of stations and "clusters" in many markets, formats fragmented. There is simply no reason for a corporate owner to compete with itself in a given market. The days of innovative station owners such as Gordon McClendon and Todd Storz are long gone. And the huge debt acquired as the radio consolidators started buying stations means they can't afford to take a chance with programming. 

In every aspect of American life fewer and fewer are in control of more and more .

@lowrider57 you mention a current hit factory...how is it different from Motown or Stax, etc.? I'm 38 and tend to think that I listen a wide range of music but I'm sure when my 2 1/2 year old is a teen, he may think I'm a musical schmuck as well. 

It's also important to note that not all music is made for you. Why would I sit here and spend time railing against a Taylor Swift album? It's not for me...I'm sure T Swift isn't sitting somewhere with her 6 string saying to herself "hmmm...I bet dudes pushing 40 will love this song..." I can say the same for Country music...something I will never ever understand but I can appreciate that many people do. 

You may not like what 'the kids' are listening to these days but It's important to understand what they are listening to because it's their soundtrack. I do not specifically care for trap music, Migos, Drake, Lil' Uzi Vert, etc. but this is what a lot of teens/20's are listening to at the gym. If I want a chance at identifying with them and staying somewhat relevant you have to understand what they are listening to and where it's coming from...

I hope I never become an old guy waxing nostalgia about Kurt Cobain (and the like) to anyone who will listen...my worst nightmare...