To be fair, the planet in Journey's End wasn't a full member but a colony world, which means they don't have the same rights as a full member. Plus, I think the

To be fair, the planet in Journey's End wasn't a full member but a colony world, which means they don't have the same rights as a full member. Plus, I think they just settled on that planet which would mean the planet isn't under Federation jurisdiction, just the citizenry (provided they're Fed citizens). Additionally, the Cardies have either a similar or better military compared to the Federation, and the treaty helped prevent full out war (that later showed up, but in the form of the Dominion War). Giving up a few planets with small populations doesn't seem all that bad for stopping what could've been the largest war in the quadrant. As for Insurrection, it's commonly accepted that Dougherty was working alone, without the support of the rest of Starfleet or the Federation. It's not implausible, considering he was an admiral and could very easily order ships places without much questioning. The Son'a are nowhere near as advanced as the Cardassians, the Federation could easily take them if they tried to start something.