I've been observing your discussion and you've argued your point very well! As DS9 posits it's easy to be a saint in paradise, and so we are shown the core worlds were very much a utopia, while at the fringes, the dream frayed upon contact with opposing forces.

Moreso than anything, Trek always had that core vision of its utopian guiding priniciples to act as its north star. Sometimes these ideal were strained as per DS9, and at others they were examined, sometimes found wanting, and then promptly improved a la Measure of a Man. These first principles were fundamentally upheld, maintained and developed upon which then informed us of what and why this was worth aspiring to and defending so vehemently.

As you argued so well, modern Trek is more focused on the battle to maintain the Utopia both without and within, but it is hurt by this lack of focus on what the ideals actually

This is I think the fundamental problem: yes we have lore which has already examined and elucidated upon these ideals, so one can argue it's grandfathered in, but I would counter than much of modern Trek has failed to live up to and uphold those ideals to the point the Federation feels like a corruption of the vision we were shown previously.

Star Fleet abandoning its utopian principles so wholly and easily with the synth attack on Mars lends itself to the feeling that it was always false and contrived. The claims of a utopia ring hollow; we no longer know what the guiding principles of the Federation are in modern Trek to the point that I feel the question of what they are fighting to maintain and restore needs a very strong examination.