The music in TNG and all the subsequent Trek shows is the aural equivalent of wallpaper.
I would agree, except I would qualify it as TNG season 4 and later. TNG seasons 1-3 had some pretty darn good music. When Dennis McCarthy was let off the leash, he could write some very good music. And Ron Jones was excellent as well. I really like the season 1 music, which is far more melodic and makes uses of recurring themes and motifs, including the main title theme. And then, of course, Ron Jones' score to "The Best of Both Worlds" is outstanding. Even early season 4 has some good scores, such as Jones' score for "Booby Trap."
It was only around early- to mid-season 4 when they canned Jones and put McCarthy under tight restrictions that we ended up with sonic wallpaper.