Customer expectations are one thing. Meeting them is another. Perhaps you have read accounts where a buyer worked closely with a custom bike builder only to be disappointed with the outcome. Qualitative metrics are one thing. Creating a bicycle is not qualitative but rather a quantitative process based upon physics. Every time, a single dimension is changed on a bike frame, its mechanical properties change. A custom bike is a swag. A guess.
This nexus isn't easy. Schwinn for example after making many bicycles for many years got it wrong and went out of business.