It comes down to giving the user the confidence that they have set up the thermal model using the correct amount of power. More often than not, this value is known as watts (for electronics, this is an output of an electrical power analysis done by the Electrical Engineers).
The current workflow involves extracting the volume from CAD, and putting that in a spreadsheet along with the power (output from the EE), and calculate the Watt/m^3. This introduces an extra step, with the potential for human error.
If you can’t provide an output easily, then can we at least allow the user to just input a “body heat load” in Watts?