> I could make up a logical argument for the first revision needing to be parent but > that would suck in reality as they often are the most bugged and least attractive > version. The region argument is totally different.
This is one of the things that has always bugged me about MAME.
Organizationally within MAME, the games should follow a proper parent-child relationship based on the way the ROMs are shared between sets. Every set should be named with a long name that fully describes the set. i.e. no more 8.3 set names.
Then, there should be some sort of software list in MAME that maps the old short names to whatever set is considered the best/definitive/playable/whatever version that we currently call the "parent". That way, people can always run "mame asteroid" and it just runs whatever version is currently considered the "best". This should also result in less churning of the set names when a newer revision is discovered.