What is the argument for evolution, for why we have no vestigial organs?

As usual, "secretsauce" (above) has the straight story here, and it would be hard to improve upon his answer. But there is more: evolution is now a proven fact, which means that any criticism of it is necessarily erroneous, and no such criticism need be considered for anything other than pedagogical purposes. For further study, one can scarcely do better than: