I've been listening to a 182 song playlist on Spotify that someone put together. It's a mix of anything from Nirvana to Matthew Sweet to Pearl Jam to Marilyn Manson.
No matter who it is, the recordings just sound more.....live. More breathing, more air, more dynamic. It's hard to really out my finger on it, but on a good sound system, many of the songs are like you're sitting right there. You can hear the sizzle of the high hat after it's been hit.
Even the harder stuff is like that, not just the mellowed stuff.
I kinda miss the 90's, but that's the decade I really grew up in, so perhaps that's why. The music seemed more exciting to me.
Mainstream music has simply just been continually dumbed down into a background track for people rather than an emotionial listening experience. Very compressed tracks make it easy for people to listen to on low quality headphones or quietly on their computer speakers or in their car. Of course the loudness wars have to do with it as well, you don't want your song consistently 10 db lower than the song before it and after it on the radio.
There are tons of excellent dynamic records still made all the time. But nearly all the major label stuff getting made by the current most active producers is generally much too squashed for my tastes.