Why is modern pop music today so terrible?

Elvis has long been accused of merely being a white man who sang like a black man. Not so. What he did, what made him so revolutionary, was that he fused the Jump Blues he heard on "Race" records and radio shows reaching Mississippi and Tennessee, and the Hillbilly, Bluegrass, and Country & Western the white southerners were listening to on The Grand Old Opry and other radio shows. His Sun Records 78's and 45's had a Jump Blues on one side, and a Hillbilly on the other. No black man was singing Bill Monroe's "Blue Moon Of Kentucky", as Elvis did. He sang with the "hiccupping" style now associated with Rockabilly music, basically creating that music and style singing. No black man sang like that. Add in the Gospel he loved so much, and voila, you have Elvis.

I've somehow arrived at an age where-in I find myself at times lecturing the younger folk around me about how great music/radio was back during my time. It's difficult to check myself but I do.  I sound boring.  

Attended a wedding for a couple of millenials a few weeks back, spent most of the time sitting with a table of strangers, watching the "kids" dance and sing, scream while smiling into one another's faces their songs, their music. Wow. I remember doing likewise a few decades ago. 

I'm 60 now, way past the time when AM radio offered a surprising diversity. Hell, I don't know if there are even music radio stations on AM radio right now.   To paraphrase Public Enemy, "Elvis never meant sh*t to me", but I have friends for whom Elvis meant everything in terms of their personal rebellions against their parents' music. For me it was the Beatles, then Zeppelin, then...

Current pop for me is virtually unlistenable, but I have to respect the "kids" and their airtime/era. I don't belong there, I won't get it because I'm all growed up. 

Worsening matters matters are the "classic rock" stations pandering to my generation. I'd rather try to listen to current pop than wallow in the past. 

It doesnt necessarily "s*ck, it just ain't for me no more. 

Yes indeed Elvis did innovate the Rockabilly style. 

Passage of time doesn’t alter whether a musical piece is good or not .
What was an open mind at 20 would be an empty one at 80 .

I wallow in the past all day , every day , Bach is still perfection 400 years later ,

inna, there is a lot I don't understand , that's for sure .
One thing I do however is if I used your logic as a base 
 2+ 2 would equal 7 .