Recent launch of parameters in DV was highly awaited and appreciated and there are definitely other areas of usage.
One of them is (we are using in similar way session repository variables, which can be set for one-time usage via request variables in UI in metadata for some more complex and dynamic "modeling" scenarios) is following:
Allow reference of parameter values in definition of data sets - particularly referencing in definition of SQL statement for data set table (when table is based on SQL statement).
This would allow us to cover complex/dynamic reporting scenarios we currently cannot achieve in DV (and the only way is to use metadata modeling with combination of classical UI - dashboard prompt setting request variables + analysis)