The market for building complicated routings is very small -- typically only mile/segment runners. ITA's backend is already used by that community for this, but

The market for building complicated routings is very small -- typically only mile/segment runners. ITA's backend is already used by that community for this, but not sure why the public would be interested. Each segment adds additional landing fees and taxes, making it more expensive, unless you're exploiting a rare hub/partner mistake fare.