A performer should always be concerned with the technical aspects of a composition. This helps one fully understand the music and thus be able to interpret it as accurately as possible as per the composer's desires.
For the listener, it depends - a knowledge and understanding of this enhances the listening experience. However, it is not necessary because that's the performer's job i.e to bring these aspects to life to the listener, on behalf of the composer (where the composer is not the performer).
Context is quite useful as it provides a sure grounding on which a performer will base their performance decisions on. It becomes distracting when the information is taken out of context or if the information is adjudicated with a "modern" bias.
LT