This would benefit users of presenter reports. Right now it's only possible to create a new row with a row form. With row forms, unless you can default some of the columns to a value, the web user will have to manually populate all the required data in all columns. There are many cases where clients want to take a calculated result and change one aspect of it.
Some example scenarios where this would be useful: override calculated credit/pay amount, assign calculated result to a different payee, mark certain calculated pay results as approved. In these scenarios, it's only one column of the result they want to change, but with a row form they'll have to manually populate most/all of the columns for the result they're changing.
If the ICM developer creates a table that matches the structure of the data grid, then a web user should be able to create a new row in that table based on editing something in the data grid.
An additional perk would be if they can do this for multiple rows with one submit.