Thanks for your perspective.  Unfortunately one of the keys will be to simplify the front end for the submitting customer.  Adding additional custom fields would add complexity for them and additional technical debt for IT to support (thinking of regression testing needed for workflows based on customizations during upgrades).

Our customers are clinical and administrative leaders across the hospitals, they would not be able to accurately articulate the prospective IT estimates/resources needed to fulfill their request.  This estimation would fall to the Demand Managers to confirm.

Similar to @Timothy F1 comment, one opportunity may be to route all requests through a single form and let the Demand Managers make the project or enhancement determination.  Thereby the customers would search our Service Catalog for our routine services and if they can't find what they need (such as implementing a new solution) then default them to a single source Demand form.