Originally Posted by United Federation
I am not familiar with the source for those statistics. Are they canon or do they come from a semi-canon source?
As I said, I’m not 100% sure where I heard it, but I’m pretty sure that it was an episode of TAS, TNG, or DS9 that dealt with a new species’ first contact with the Federation, or their admission, or something like that.
That said, it might’ve been a semi-canon source, such as a book, however (if you haven’t found this out about me yet), I’ll take my canon bendy if it means a good story.
In terms of interspecies conflict, by the time of Kirk or later Jean Luc Picard these species had been interacting together for a few centuries. Humans, Vulcans, Andorians, and other members had whole generations born knowing nothing but the Federation. The first years of a combined Federation Starfleet probably had some interspecies conflicts, but those incidents would probably be nothing but a historical footnote by the 24th Century.
Old habits, y’know…
But seriously, you’re right about humans, Andorians, Vulcans, and Tellarites, however there are always new species being admitted to the UFP, so it would be reasonable (under that same logic) to continue the practice.
Also, there’s none so divisive an issue as forcing people into relationships that they don’t want. Look at the American Revolution, or desegregation in the United States in the 1960s, or the Irish defeat of the European Constitution. Whether it’s taxation without representation, or being forced to sit next to someone whose skin is a different colour, or ceding sovereignty to a super-national organization, people tend to become extremely angry when they lose their right to choose.
This would be a good incentive to continue less diverse starships as a common practice, to allow especially members of newer members of the Federation an opportunity to acclimate themselves at their own pace.
In any case, I’m sure that there are at least a few starships whose crews are much more diverse, to allow those who wish to work with as many relatively-alien species as possible; a rule never precludes exception.