I don't believe there actually IS a specific "vision for the future" that Trek holds to.
Well, according to Gene Roddenberry and those who worship him like he's, oh, a fat Jesus, there is.
Admittedly, I neither believe that a "spirit of Trek" is appropriate, nor do I believe it useful. Trek is what it is; it's insulting to viewers' intelligences turn it into more a philosophical system than a fictional universe, and I really dislike the attempts of Roddenberry and others to turn it into a platform for whatever political views. (For one thing, Trek trying to push a viewpoint is 99% of the time unsubtle, ham-handed, and insulting.) Whether it was Roddenberry's rather aggressive atheism or his insane belief in an "evolved humanity" which *completely kills* so much of the dramatic possibilities of humans (because, frankly, want for makes a better story than Utopia).
Personally, I
like the episodes (like so much of the Dominion War) where the UFP and Starfleet -are not- moral paragons, but rational actors in a political and interstellar relations sense. Where there aren't options taken off the table because it would be "against the spirit of Holy Roddenberry" or because of the Prime Directive (honored more in the breach than anything else, can we just accept that) or because Humans Are So Evolved...But because for whatever reason the risks and potential costs outweigh the benefits. Sometimes, that means Starfleet does -nasty things-.
(Oh, yes. Can we PLEASE see some civilian freaking oversight of Starfleet? Civil control of the military power - is that so archaic a concept these days?)
Yeah, yeah, my major in college was political science.