No one thinks that relict populations have an relevance to evolution. Darwin pointed out that wherever conditions remained constant, natural selection would prevent a well-fitted population from evolving. Today's Wollemi pines are changed from ancient ones, but retain the characteristics of ancient members of the group.
There are actually two other genera and a number of other species surviving in the Araucariaceae; at least one is abundant enough to be important in lumbering. The Wollemi pines are just a very rare member of the family.
Remember, evolution is observed daily. Creationists often confuse evolution (a change in allele frequencies in a population over time) with agencies of evolution like natural selection or consequences of evolution like increased fitness or common descent.