I whole-heartedly agree...some of my favorite current music is by Sigur Ros: half of their lyrics are in Icelandic (which I don't understand in the slightest) and half are quite literally nonsense: an invented "language" (really just quasi-systematic nonsense syllables). I can't even tell the difference between their nonsense songs and their Icelandic songs. But the music has an immense emotional impact (to me at least).
Sigur Ros, "untitled #1" (aka "Vaka"):
http://www.youtube.com/watch?v=P0AZIFmkogY
One of their "nonsense" songs, with a wicked creepy video. If you don't like the music but want to hear the nonsense singing, skip to about 2:20.
Good lyrics are a nice bonus to good music, and is very important in some music, but I really despise when certain "singer-songwriter" types obviously spend a lot of time on their lyrics, then set them to boring, cliche music. Just write a book of poetry already.