I'm reading The Mythical Man-Month, and this section jumped out at me hard. Emphasis is mine:

Most European cathedrals show differences in plan or architectural style between parts built in different generations by different builders. The later builders were tempted to ''improve'' upon the designs of the earlier ones, to reflect both changes in fashion and differences in individual taste. So the peaceful Norman transept abuts and contradicts the soaring Gothic nave, and the result proclaims the pridefulness of the builders as much as the glory of
God.
Against these, the architectural unity of Reims stands in glorious contrast. The joy that stirs the beholder comes as much from the integrity of the design as from any particular excellences. As the guidebook tells, this integrity was achieved by the self-abnegation of eight generations of builders, each of whom sacrificed some of his ideas so that the whole might be of pure design. The result proclaims not only the glory of God, but also His power to salvage fallen men from their pride.
Even though they have not taken centuries to build, most programming systems reflect conceptual disunity far worse than that of cathedrals. Usually this arises not from a serial succession of master designers, but from the separation of design into many tasks done by many men.
I will contend that conceptual integrity is the most important consideration in system design. It is better to have a system omit certain anomalous features and improvements, but to reflect one set of design ideas, than to have one that contains many good but independent and uncoordinated ideas.

It's not that I don't like Chartres; indeed, there's something incredible about projects that outlive their original intent. But when it comes to the most compelling products & systems in my life, I find conceptual integrity to be a *really* powerful force.

See also: the last section in One type of swing, etc.