MAME's philosophy is to "never look back," meaning ROMs are often updated or renamed in newer builds. This creates a need for "frozen" sets like 0.139u1 for hardware that can never run the current version.
Furthermore, ROM sets are not backwards compatible. If you have a modern PC and want the absolute most authentic experience possible, you should use the latest version of MAME and a matching modern ROM set. The 0.139u1 set is a snapshot in time, and while it’s a beautiful snapshot, it is frozen in amber. mame 0.139u1 roms list