No ,Songwriters do not just express their opinion on something, that shows a lack of understanding of songwriting, they also tell stories, express emotions describe situations all through the power and use of words.   What observer says diminishes the art of songwriting
here are examples of well crafted songs that do not express a SUBJECTIVE opinion on something.
Britains Motorways[MacColl] John Of Dreams, Unicorns, Icarus, Moth, Whitby Whaler, Song For Ireland ,Ring Of iron Three Score and Ten[W Delf].Shoals of Herring
all these songs do more than that, they are not just an opinion, and to try and claim such, only belittles the songwriting

I have np problem with someone who can only concentrate on lyrics for a short while, like mg.
Alan Conn, yes of course when music is in a foreign language you listen to it differently from how you do if you understand the lyrics.
    but the OP is talking about lyrics when we understand the language,This is primarily a forum where english and american is the spoken language and the OP is talking about the american folkscene and the uk folk revival and the english american language
Furthermore, in reply to observers comment
"Just because a song writer considers their lyrics important does not mean that they are actually important, relevant or meaningfu"
Bonzo and Observer , to decide that you have to feckin well listen first. if you do not listen to the words, how can you decide if they are meaningful, to decide if they are meaningful you have to have listened..
Bonzo . claims he is only interested in the sound good voice and backing, so it would appear he is not interested in the lyrics , yet   he agrees with the following statement from observer
"Just because a song writer considers their lyrics important does not mean that they are actually important, relevant or meaningful
   THAT MEANS BONZO DOES ACTUALLY LISTEN TO THE LYRICS otherwise he could not make a value judgement as to whether they were meaningful. Here is the lyrics of ENGLAND's MOTORWAYS

Come over here, my little son, and I'll tell you what to do
Undress yourself and get into bed and a tale I'll tell to you
It's all about your daddy, he's a man you seldom see
For he's forced to roam, far away from home, far, far from you and me

CHORUS
But remember lad, he's still your dad
Though he's working far away
In the cold and the heat, all the hours of the week
On England's Motorways

So if you fall and hurt yourself and get up feeling bad
It isn't any use to go a-running for your dad
For the only time since you were born that he's spent some time with you
He was out of a job and he hadn't a bob, he was signing on the buroo

CHORUS

Sure we'd like your daddy here and wouldn't it be fine
To have him working here at home and be with us all the time
But beggars can't be choosers, so we have to bear the load
Cos we need the money your daddy earns, working on the road