However for argument sake if music must have words/lyrics. The question arise about the role words play in music and how best to used words to compliment music to become a whole greater than the sum of it's part.
One proposed method is to simply merge the genre of poetry with music. Simply judge lyrics by the standard of poetry. Therefore the lyrics should be judge by how creatively it expresses any ideas, emotions, concept etc. so poetic elements like word play, rhythm/meter,metaphors, rhyming, imagery etc. are important in judging the lyrics of a work.
This belief that lyrics should be poetic results in the type of criticism I've read of lyrics that it is "overly-literal" (a complaint I've read in the ranked Radiohead songs article).
However it has to be stressed that these devices are important in poetry as the entire interest and expressive content in poetry is 100% in the words. Therefore the words has no choice but to be set in a creative, interesting evocative manner. The words has to paint a picture or emotions on the audience all by itself.
I don't necessarily think it's wrong to have poetic elements in music but I think it's has very little positive impact on personal enjoyment of the music.
My view is that words has to be complementary to music. That words and music should fulfil a role that the other elements can't achieve.
For this we have to look at the strength and weakness of music as a genre of the arts and how we can used words to cover up the weakness of music.
The unique strength of music is that it is the language of emotions. A person telling another person how they feel will be hamstrung by a) language barrier and b) reliant on the person to have enough similar personal experience to empathised with the person. Even then they can only imagine how the other person is feeling but they can't know how the person is feeling as they can't read people mind.
Music cuts through that barrier because the audience who listen to that music can understand the emotions the artist is expressing because the music forces the audience to feel the emotions along with the artist.
I can't understand how Beethoven feels if he told me in words as I can't understand the German language but I can understand how Beethoven feels in his music as I felt it with him as he forces me to feel it when I am listening to it.
I do believe that you can get a reasonable consensus of the emotions the artist is depicting via their music and that consensus can cross language and cultural boundaries.
However music does have it's limitation is that it has no literal meaning whatsoever. Sure I can understand how Beethoven felt when listening to his 5th Symphony but whatever details in his life that led him to feel that way and express it via music can only be known via words. That's the reason why they may be concensus about the emotions expressed in music, there is a wide divergent opinion on what exactly the music represents. Is the Eroica symphony a representation of napoleon Bonaparte or is it a representation of Beethoven struggle with deafness etc? listeners often used their own details in their personal life that elicit similar emotions that the work is expressing as a personal represention to what the music is about (for example Beethoven 5th symphony is a representation of a person with depression undergoing cognitive behavioural therapy, however I know that I only see it that way due to my own background and the fields that I study in).
If instrumental music is the language of emotions and the literal meaning is derived by the audience own unique life experience that differ to the creator
Then the words in music primary role should be to provide the literal meaning that would have been subjectively provided by the audience own life experiences in instrumental music.
Words should provide the literal framework of the emotional expression that is present in music.
The music expresses the emotions, the role of words should be to fill in the details and explanation and the rationale behind the emotional expression. So the audience not only understand what emotion the musician is expressing but also the rationale behind that emotional expression.
Hence the criticism of "overly-literal" lyrics is completely nonsense as literal lyrics is a perfect division of labour between words and music. Only literal lyrics can effectively compliment and cover up the weakness of music.
Creating lyrics with no objective literal meaning and using lyrics to paint a picture or emotions is an inappropriate allocation of resources as that role should be done by the music and hence does not fully integrate the merger of the unique aspects of the two art forms.