Why creating a fresh log file is called log rotate instead of log refresh or log delete? What does the word rotate emphasis?
It's called logrotate because typically it is used to "rotate" logs to new files periodically -- that is, it doesn't delete or refresh them (at least from my interpretation of those words).
One definition of "rotate" provided by the Random House Dictionary is:
to cause to go through a cycle of changes or follow in a fixed routine of succession: to rotate crops.
logrotate does as described -- typically
log.2, etc. They are not typically deleted before they reach the threshold -- log deletion is not the primary function of logrotate, rotation is.