Because most researchers don't know ahead of time respondent preferences and importances, we take the safer approach of assuming no prior preferences when generating experimental designs for CBC. Such designs have proven robust over the years for the general researcher and in the general conditions.
For advanced researchers who have prior knowledge about utilities and want to use that information to create higher D-efficient designs, they could create their CBC designs using a 3rd-party software approach and then import those designs into Lighthouse Studio such that our software fields them.
The danger with using prior utilities to develop designs is if you are wrong. The downside risk is potentially worse than the upside benefit.