^I'm willing to wager that the UFP in the 29th Century is quite different from the one we know in the first half of this millennium. I mean, the United States has changed a lot in the past 230 years so imagine twice that for the Federation, not just in size, but in politics, values, and technology...
They may consider the 24th Century humans as not so enlightened, humanity's view of space travel would be very different from today. By then, Humans would have been going to space for 900 years, warp capable for 8 centuries, all the places we saw Picard and Kirk explore as familiar to the 29th Century Federation as our hometowns are to us. Change would be tremendous especially if the Romulans and Klingons joined. It would mean the Federation political landscape would be completely alien to Picard, Sisko and Janeway. They would be dealing with powers beyond what was Romulan and Klingon space.
Not to mention all those pre-industrial societies we saw in TNG. Imagine a region of Federation whose stability is threatened by a centuries-long war between the Malcorians and Barkonians, border disputes with the Devore who had finally expanded into the Beta Quadrant, and an tense alliance with a race that toppled the Dominion in the Gamma Quadrant.