Good word, Asking, you've hit the nail on the head.
In my experience, this issue has centers largely around the Creationist misunderstanding of the term "vestigial". This term does not mean "useless", but rather "previously had a different use".
The most obvious vestigial structures, in my opinion, are the vestigial wings on flightless birds. These wings indisputably still have functions (heating, swimming, running acceleration, mating displays, etc), but they also were quite obviously meant to be used in flight (nearly all vestigial wings still clearly show the airfoil pattern required for flight, and their bone structures and muscles structures still show the same patterns as flying birds.
Thus, a vestigial structure is not a useless one, but rather one that once held a different function.