A photograph is like a Thanksgiving dinner. It has many components, all of which are important. Nobody scoots back from the table and says only "Wow, that was good turkey!". They always say it was a good "dinner", which includes everything, turkey or otherwise.
Sharpness, blur, contrast, exposure, composition, lighting, timing, abstraction, color, tonality, etc. etc. are all important.
Consider a photograph in relation to Gestault Theory, which says the whole is a sum of the parts. It's the unified whole that a viewer actually perceives.
Think of it in the way Rudolf Arnhiem put it in a 1971 essay titled "Entropy and Art",
"When nothing superfluous is included and
nothing indispensable left out, one can
understand the interrelation of the whole and
its parts, as well as the hierarchic scale of
importance and power by which some structural
features are dominant, others subordinate."
Sharpness and blur are just compositional tools that help position structural parts on the "hierarchic scale of importance and power". It can't be over emphasized if the effect it produces is appropriate. If the effect isn't appropriate the tool isn't being used properly.
A photograph is like a Thanksgiving dinner. It h... (