Why is modern pop music today so terrible?

First off, music is pretty subjective. Besides todays music isn't for you. You don't get it because your not suppose to. Last thing kids want is their parents, or worst their grandparents to be tripping on their music. Have we gotten so old we don't remember our parents. My Dad ( God bless him, he's no longer here but still love and miss him ) didn't like The Beatles, couldn't stand Stones, hated Alice Cooper use to call him the freak. What I'm trying to say is, welcome the club Grandpa. Ah Grasshopper, the circle is complete, we've become our Parents. 

One word... Compression :/

"Why is modern pop music today so terrible?"

Because it's an honest reflection of the times that we live in: pop music for mass consumption is superficial, artificial, meaningless and 100% disposable.  Here today and gone later today.  It wasn't always that way imo.  

It is what it is.  And most of it is God-awful and execrable.

There.  Spoken like a true Old Fart.

I'm not an old fart lol, but I agree with that statement as far as the music itself and not the actual recording process. It's cheap and the easy way " 2 takes and we will fix it in post" most the time the music itself in prefabricated and auto tune inhanced vocals laid down on top, You look and the garbage sampes supposed artist like Diplo, sleepy Tom, M82, the weekend are laying down. even that Justin temberlake dude and honestly you would think he would know better as long as he's been an artist. It's just crappy home studio garbage. you will notice that there is some that do, do a good job spend massive amounts of time in the studio to get it right. But they are really few and far b/t. 

One of the truest old sayings is" The Good is the Enemy of the Best !"

If you settle for good it inevitability becomes fair which over time degenerates to bad

Bach is Best .