So, lack of writing skill can draw further attention to political slant in fiction. Because the execution of an idea is a part of telling the story effectively. And, sometimes folks just fail in that regard. But, seamless presentation of a political/social/cultural idea isn't a requirement for being an author.
Worldview, of course, does play a role. Things that challenge our personal views will stick out more than those things which are already a part of them. Thus liberals are more likely to complain about conservative "messages" and conservatives about liberal "messages", and we too frequently assume that those things stand out to us because of lack of craft, but that's only sometimes the case. (I have a friend who hates government social support systems. He wrote a book in which the protags mother goes on welfare and then never does anything else because it's more appealing to sit at home and get free stuff. I disagree with that particular take on the issue, but it was compounded by the fact that this information is *told* to the reader, rather than shown. Just a block paragraph of text in which the narrator tells us protags mother is lazy and worthless and on foodstamps. So yes, craft is an issue too. But then, craft is always an issue with creative work.)
Also, ideas about what folks value as creative change. Warhol was ridiculed for his "pop art" by the "real" artists of his time. Now we look at his work as being pretty avant garde. I imagine readers follow similar shifts in direction as new authors try new things.