In some ways the XML does produce some good results though for people wishing to actually play. For example that Commodore 64 TV console with included games. Not sure if it is working or not but that is a cool addition that was not there before.
However it is not an arcade machine.
Not suggesting the changes are ill thought out but from a project perspective I would kind of expect a rebranding and name change too rather than Multiple Arcade Machine Emulator. Maybe that is in the works?
By the way @Ciro - I am doing the same, filtering out stuff that has a software list and not that we can not anyway but mostly keeping everything else MESS related.