Many times we do surface modelling and play with thickness parameter to make solid appearance and after we get desired form we just need to convert it to solid. i am suggesting above option to directly doing it from the same window.
Currently, we have to do multiple steps like turn off thickness first and then do offsetsrf command with same thickness, flip the surface etc. but a straightforward way for doing that will be much faster. the option may be called as “convert to polysurface”.