Why does all new pop music sound the same?


Basically because it IS the same - I think anyone with ears already knows that, but there is more to it. 

https://www.youtube.com/watch?v=oVME_l4IwII
chayro
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... 
Because in order to be popular these days it has to be generic enough to appeal to more diverse kinds of people in a vary basic way than ever. Much like fast food.

Better off forgetting about what is popular or promoted heavily and find your own good music. There is more of that out there than ever these days and growing. Its all up to you not others to find the music you like. The tools and material to do it is all out there. Some of it might even turn out to be or have been popular.

Don’t be afraid to go way back if needed. Great music was made and recorded as far back as the first 3rd of the 20th century and digital remastering and streaming works wonders. Way before The Beatles hit. Go figure!