That's the biggest hangup I have with evolution. It depends on a destructive influence, mutations, to bring about something constructive. That's like trying to build a house by repeatedly smacking a bunch of lumber, plumbing fixtures, and electrical wires with a wrecking ball. I suppose once in a great while, you might get two boards to line up just right by sheer coincidence, but the next hit from the wrecking ball would undo that progress, if not completely shatter the boards and make them useless.
And yet, the majority of people would rather believe that's the way houses get built, instead of a team of construction workers putting their knowledge and skill to use to design and build it.