I've never seen that argument before .. Looks a bit to me like you've made up something to argue against.
I like lots of music by bands that never really concerned themselves too much with messages. Just throw a glance at the many content Canterbury bands from the 70s. Or another example; I very much like the album Tarkus which is about a half-tank/half-armadillo. I don't think any of the sane people I know would stand behind the proposed argument you present and oppose (that LZ fails artistically).