Clearly Linux is one of the most successful products ever. Let me quote a little bit from Linus Torvalds and other brilliant people involved in it:
"A strong vision and a sure hand sound like good things on paper. It's just
that I have never _ever_ met a technical person (including me) whom I
would trust to know what is really the right thing to do in the long run.
Too strong a strong vision can kill you - you'll walk right over the edge,
firm in the knowledge of the path in front of you."
"The most successful software have born from fixing/patching an
initial/simple implementation while the greatest software failures
have born from deep planning and design.
More specifically, the following article is a great read
Evolutionary Database Design