Provide the report writer the ability to add calculated columns through the Modeling tab in PBI Desktop, when the report writer has sourced a common data model (Get Data>Powerbi Datasets)
At current, although the report writer has build permissions to the common data model, they are not able to add a calculated column.
Currently, the product allows a report writer to create a Measure, but not a calculated column. You would typically expect the report writer to be able to create simple calculated columns such as first-name and last name concatenated together, or to make a simple case statement to say “before this date = A, and after that date = B”. Don’t think of it as a modification to a table, but more like a measure (an on-the-fly calculation) at the grain of each row. This SHOULD be something on their roadmap. From the PBI team’s perspective, we view this as a pretty important capability to allow report authors to create a purpose specific, or analysis-specific simple calculated attribute