For what you are doing at the moment it will not matter. The OBJ2CR2 script requires that the model contains a complete set of UV data. Good, bad or indifferent it will not matter, but if the data is missing or incomplete then the script will not run.

Most modeling applications apply some form of UV mapping to the whole model by default, however Hexagon does not. Hence the need to give the model a quick once through UVMapper.

Later on in the project you can go back and refine the mapping to best suit your texturing needs. Experiment with the different options, it is often the best way to learn.