That's the key here; 'mainstream' music. Simply put, that is just one tiny world out there, it just gets the most money and promotion. But we get this inflated idea that it's the majority of stuff out there and it just isn't.
There's a whole other argument that mainstream music isn't worse at all and I I am actually inclined to believe it, despite hating it myself, but there were some utter dog shits in the 80's and so on, too. One point is, though we have simplified harmonically and lyrically - traditional values we consider as 'good', we are focusing more now on texture; colour, tone. The quality and range of unique sounds has proliferated and the art of creating those sounds is something most of us don't know how to appreciate. But as someone who knows, I'm often impressed. But yeah that's a whole other debate.
As for 2020 quality, well... as you can see in the other debate in this chat, that's totally subjective so I couldn't presume to know.
But, some very new stuff I've been enjoying:
GoGo Penguin is pretty great trio with some new content. some kinda... jazz electronic... thing. Just listen.
Jacob Collier (in post) has his latest album 'Djesse volume 2' and is relating 3&4 soon
Bon Iver has been releasing some new stuff
Jonsi for some post-rock, has finally released more content
And one more drop, I like to find new creators through these Jazzhop Cafe streams
And for contrast, Dustin Tebbutt has some new stuff too
There's a world out there's I'm barely scratching the tip of a hair, though. It's fun to discover =)
RE: Music hasn't gotten worse. YOU have