It would be neat, sure, but uh... what would you put there? Really, other than name and some gameplay concepts the only thing the games all have in common is... Chocobos. Crystal might work, sure, but they aren't even in the plot in at least 4 of the games.
Personally I don't like the idea, I doubt I would use it, but if someone else really wants them, then I say go for it.