Hi Geebo.
I totally agree on this issue with you. I missed this future so much since Civ III.
I am not often at site any more too, (since, it's completely taken over by bunch of ignorant posters, probably very young or immature, anyway, that just whine and trash the game. Or to put it more fairly, new generation of PC game players that are completely different opinionated than me, at least) and one of the reasons I logged in is just to give you support for this.
I have to play only Pangaea for this reason (because I can at least pick civs that are somehow connected historically or/and geographically one to each other) and continents I do not play anymore (since Civ III) at all, because of this (since I would prefer to have FE on one continent Inca, Maya and Aztecs and on the other Spain, England and France but this is not possible to accomplish, so I gave up on Continent Style map entirely).
I think, also, it is not hard to implement. So developer, please give us this option in Civiliyation V game, no need to wait for future (if there will be any) civs. Thank you.