Modularity and Arthur's Third Law

Via the NYT comes this link to Edge's Annual Question. This year Edge called for submission of natural or psychological laws named after their discoverers. Here's one of physicist John Barrow's submissions, Barrow's Second Law:

All difficult conjectures should be proved by reductio ad absurdum arguments. For if the proof is long and complicated enough you are bound to make a mistake somewhere and hence a contradiction will inevitably appear, and so the truth of the original conjecture is established QED.

On a less frivolous note, also interesting was Brian Arthur's contribution, Arthur's Third Law:

The modularization of technologies increases with the extent of the market.

Just as it pays to create a specialized worker if there is sufficient volume of throughput to occupy that specialty, it pays to create a standard prefabricated assembly, or module, if its function recurs in many instances. Modularity therefore is to a technological economy what the division of labor is to a manufacturing one—it increases as the economy expands.

This observation seems parallel to and evocative of Clayton Christensen's thesis that industries tend to evolve (along the trajectory of technology improvement) from a phase of not-yet-good-enough (characterized by integrated, highly interdependent architectures) to a phase where the performance is better than good enough, at which point there is an industry-wide shift to a more modular architecture. So which is the fundamental driver for the migration from integrated to modular architectures - growth in size of the market or technological advancements?