Well it's like I said, SEGA did all the heavy lifting in the 90s. The data is in there but I guess none of the DAT creators bothered to look. That or they don't know how to properly utilize the data.
Open any master system through 32x game in a hex editor. The first 256 bytes or so are all the pertinent info on a game in plain text. Local title, international title, release date, controllers supported, catalog id number, unique checksum, release regions, cart revision number and sometimes more. Saturn and Dreamcast games also have this data, but due to the inherent craziness of disc-based systems, it's a bit harder to scan for.
About the only thing that might not be in the dat is the full title of the game. Due to size constraints sometimes a ridiculously long title might not fit.
I need to make sure I have a complete set, but with the internal info and the no intro game titles I could probably make a fairly complete dat. A tool could be made.