Why is the SD of a set of scores usually a more useful index of scatter in those scores than the variance?

Question

Statistical interpretation... SD is standard deviation

Answer 1

The SD is a measure of the scatter in the same units of the scores. The variance is a measure of the scatter in the square of the units of the scores.
This is why formulas such as z score conversion use the SD.
(This is why in engineering applications the SD is called the root mean square.)

Answer 2

The SD is just the square root of the variance. That doen't make it better. It will have the same units though.