Comment by worstspotgain

Agreed, and well put. I should have emphasized the role of uncertainty in the architecture/complexity relationship.

In your example, you have a minimum of 4 cabinets. If you start out with N>=4, architecture and complexity are inversely related (to a point of course.) They are sometimes directly related when 1<N<4, and most often are when N=1.

We're predicting the future path of N. Adding a subsystem and a formal internal API when N=1 is being bullish on N, trading the present for the future and expecting a good rate of return.