In many ways being able to run something on a stable, well emulated, platform can be a better way to know some tool will always be around than to have the source code for the tool itself (even if that is definitely also a good thing). There is a much better chance that someone will e.g. keep maintaining some forks of DOSBox to keep it running than that there will be people around to maintain a specific tool. Not sure how that looks for MacOS applications? Of course support for running fully offline and without messy DRM is a must.