This is a great question. Etymological studies can prove very useful when scholars seek to find meanings of unattested words through comparative linguistics, but when it comes to interpretation, etymologies are almost never necessary. What a word meant in the past or how a word has developed over time has little bearing on interpretation.
For example, to know that the word "nice" comes from the Latin word “nescio” (meaning, not to know) is a point of historical interest, but this does nothing for interpretation. In fact, it can make an interpretation anachronistic and simply wrong. Neither the author, who employs the word, "nice," nor the reader has the historical development of the word in mind. Hence, the interpreter should stay away from etymologies.
The only exception is when the author shows awareness of the etymological development and signals this to the reader through contextual clues. The danger of using etymologies must be emphasized in view of the penchant to make elaborate points through etymologies.