Two things:
(1) No it wasn't, not at all. Many Google searches later & most places say it's merely a matter of aesthetic/statistical preference; the game itself didn't tell us so, and most players don't know how to scour Live Letters or research such hardly touched on topics... most places delineate the choice as superficial.
Even in-game, all you receive is Minfilia essentially telling you to 'go with your heart', to whichever GC delivers the most rousing speech... not much in the way of telling you the choice will have ramifications on playability with friends or gameplay, period.
I've even read a few places people expressing that Yoshi-P essentially told us our choice of GC shouldn't make a substantial difference... I'd consider being forced into a GC I don't like in order to Frontline with friends of different tastes in GC very substantial (especially when significant searching seems to point to the conclusion it's a trivial decision with little-no bearing on playability).
(2) We are forced to change GC's if we want to Frontline alongside a friend of a different GC Affiliation. It's cute when people ignore the context of such points.
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