It was not included because it was not written for that purpose. It was written from a raw single mame version. It was not written for people that use retropie on a PC..because I never knew you could do that at the time. My thought was why use a retroarch core for mame on a PC when you can use the stand alone exe which is more updated and runs better? Emulation Station using RetroPie can build a list from the games database (I think) (if you are off-line you are outta luck!) Atrract Mode was not made that way..extra coding that was not needed at the time.