Because first and foremost for Christians is truth. And evolution is not truth. Tell me about irreducible complexity at the cellular level. Tell me about the thousands of missing "missing links" representing the incremental changes between one specie and another. The truth about a Creator is plain. *That* much doesn't require a degree in science....
That would be a waste of time. Showing any facit of Evolution to be false proves nothing about the truth of Creationism.