While civility and social contract theory may explain this phenomenon in part (no one wants to be a jerk, right?), an interesting construct may explain this more fully: The Willingness to Self-Censor.
According to psychologist Andrew Hayes, some people are more willing to withhold their opinion from those they believe might disagree with that opinion. Rather than sharing their opinions freely, they wait until they are in a comfortable place to speak, where they are free from being critiqued. Or they simply do not reveal their true thoughts at all.
This theory, I believe, has important implications for writers. Some of us (and I put myself in this category), might score high on the Willingness to Self-Censor Scale. While we may feel we are protecting ourselves, we should consider:
1. Not surprisingly, as Hayes explains, self-censors are more likely to be "more apprehensive about communication." Are we writing as well as we could be, if we are constantly censoring ourselves? Maybe we are limiting our voices by not digging deep enough, by not bringing every emotion and opinion to the page, by not freeing ourselves. Maybe the fear that people won't agree with us, or that they won't like what our characters do or say, keeps us from writing at all.
2. Self-censors also "fear negative evaluation to a greater extent" as compared to those less willing to self-censor. So not only does self-censorship negatively impact the ability to write honestly and deeply, but it also impairs the self-censor's ability to withstand critique. So perhaps, writing more honestly will help free us from our fear of other people's criticism.
But what do you think? As a writer--are you writing as openly (less willing to self-censor) as you could be? As a reader--do you appreciate openness and rawness on the part of the writer?