This sounds like a good proposal, though I expect that it might go both ways where someone else might prefer for the inspector to not be launched automatically
I know others who just leave the web browser with the address:
localhost:21000/inspector always running on a separate monitor.
Have you considered perhaps writing simple batch/shell script that launches the browser to that URL? If you are specifically intending for the browser only to be launched when SpatialOS has started up, I suspect you could possibly poll the output for the
SpatialOS is Ready string or perhaps check for the presence of the logs before launching the browser?