Sorry, the title of the question is wrong!
Does the following sentence mean "The main message of Benjamin’s article was a call for art to become independent and for artists to make clear positions (not to be neutral) in the class struggles of the day"?
p.s. At first, I had mistyped "neutral" that is corrected now ;)
The leitmotif of Benjamin’s essay was a clear call for art to shed its autonomy and for artists to take up a stance in the class struggles of the day.