Comment by imtringued

I think the primary strengths of a text based format would be in defining the assembly of parts and parameterizing them.

E.g. you want to build a gear box so you draw a sketch in the GUI with the positions of all the gears and name each axle where a gear would be attached, then you open a text editor where you specify all the gear parameters and to which axle they should be attached to. You then go back to the GUI to move the axles around. After assembly, you can start designing a housing for the gearbox.

The assembly could then be loaded directly into any simulation environment of your choice.