Bad Concept: Obviousness

Consider this - what distinguishes obviousness from a first impression? Like some kind of meta semantic stop sign, "it's obvious!" can be used as an excuse to stop thinking about a question. It can be shouted out as an argument with an implication to the effect of "If you don't agree with me instantly, you're an idiot." which can sometimes convince people that an idea is correct without the person actually supporting their points. I sometimes wonder if obviousness is just an insidious rationalization that we cling to when what we really want is to avoid thinking or gain instant agreement.

I wonder how much damage obviousness has done?