Ok, lets turn this around: Why do Fundamentalist believe in such a weak god that is a poor engineer?
The rest of the universe is governed by a set of consistent, rational laws that allow the universe to run on full automatic. Why would God design biology to work different and require constant hands-on-control.
Creationists have a weak, stupid god that built a universe that requires constant tweaking. Their god is a poor engineer. It makes more sense that biology would work like the rest of the universe, self correcting, self regulating, and self modifying. Thus, His creatures can change as their environment changes. That is all evolution is, the plants and animals adapting to their changing environment (That is glorious!).
Evolution is an extremely elegant solution to life on a planet with a changing environment. Only a Master Engineer could come up with such an elegant solution for a self-correcting system. The Creationists severely limit God's intelligence and engineering ability by saying He had to sit and create everything by hand when the whole system is automated. Seems disrespectful.