Very often in our design choices we face a choice between a hierarchy model and a "flat" model, as explained in the knowledge base article Alternative approaches to modelling Finance Reporting in BOARD
Most of the time we can manage with one approach or the other, but in some cases it leads to something more complicated than necessary.
Requirement: represent both a hierarchy and calculate intermediate elements on the fly with specific rules.
Example (from a SAP BW report) with % and margin calculations are integrated with a collapse presentation.
Workaround : currently we either do everything flat (which leads to more complicated rules and layouts) or we materialize some subtotals (which leads to long calculations and "pollutes" the cubes with unnecessary values).
Authorize the simultaneous use of rules and related entities in a dataview.