As Alan Moore once said, "Utopia is a verb."
Beautifully put.
Then it takes that same impossible org 218 years to get the first integrated ship?
It's not the first try, though. I established in
Ex Machina that the refit NCC-1701's unusually diverse crew (compared to what we saw in TOS and in later movies) was the result of a conscious effort on Will Decker's part to increase crew diversity in Starfleet. And I tied
Orion's Hounds into that by describing how Decker's efforts hadn't really caught on persistently and the
Luna class project was an attempt to revive the principle. There may have been other such attempts along the way, since we've seen various ships in the novelverse that were fairly diverse; but it's the sort of thing that can fall by the wayside if a steady effort isn't made, so its application has tended to be piecemeal. (Which is to justify why some books portray diverse crews and other books, shows, and films portray overwhelmingly human crews.)
Of course, technology is also a factor. I've talked about how 24th-century technology makes it fairly easy to accommodate species with different anatomies or environmental needs aboard th same ship, but that might've been a more difficult thing to achieve in earlier eras, which is part of what kept Decker's efforts from really catching on. It was just easier to segregate by environment. But by the 2370s, the tech is sophisticated enough that the obstacle isn't there anymore.
Also, one thing to consider is that the mixed-species crews we've seen elsewhere, with the occasional exception like the
da Vinci, have mostly been all-humanoid crews. It's easier to accommodate a bunch of species who share a common body plan and basic environment. What makes the
Luna class distinctive is
not that it's the first attempt to mix human and nonhuman crew, but that it's the largest systematic attempt to integrate humanoid and nonhumanoid crew. So there have been plenty of ships that have had large numbers of Vulcans or Bolians or Betazoids or Andorians or what-have-you, but the
Lunas are innovative in that they're designed to be accessible for species as diverse as Pahkwa-thanh and Irriol and Pak'shree and all the rest. So it's the next step beyond integrating the humanoid species.