It doesn't.
Much of it just doesn't fit your embedded criteria for acceptable music. Look, every decade/generation has its share of totally shitty music. The 70's, 80's, and 90's (especially the 90's) all had a factory's worth of bubble-gum bullsh*t with generic styles, voices, personas, and faces. Those artists always get the limelight because they appeal to the superficial acceptance factor of much of the music-gobbling population.
However, to say that most new music sucks is to say that you're unwilling to leave your own perspective and acknowledge the very immediate, very available musical artistry that's out there today. Artists like Adele, The National, M83, Taylor Swift, Lemar, Band of Horses, Sufjan Stevens, Nas, Jay-Z, etc., are all as talented and influential as anything done in the last three decades. I don;t have to like them, but I have to admit their sheer talent and dedication to their craft.
I mean, Zep may have broken new ground, but new artists simply continue building the road that Zep started years ago.
Hell, even your list of artists you grew up with (all of whom I share your reverence of, if not your complete idolatry), share much with the current crop of musical avante-garde and illuminati. And artists like Rush - who just last year released their best album since 1981 - , The Police, Tears for Fears, Talking Heads, and others will remain my musical benchmarks - but not to the whiny exclusion of the musical zeitgeist.
Admittedly, modern engineering is geared way too much towards radio production, with all its compression and limited sonics and target audience who doesn't give a shit about high fidelity. But as music has become so niche-oriented, there're plenty of artists and music out there that can satisfy you.
If not, you might as well go on Eagles tour or cough up $500 for a Stones ticket. It sounds as if your stone gathered moss long ago.
IMHO, of course.
