The Overlord wrote:
Sometimes there cannot peace between nations, if a particularly bad regime exists is power in one of these nations. As long as the Nazis controlled Germany, there was never going to be peace between Germany and its neighbours. The same deal with Cardassia, as long as Cardassia was controlled by a military, there would never be peace between cardassia and the Federation, there was only peace after that government was gone.
You cannot compare intraspecies and interspecies issues. I am all for waging war against imperialist forces like the nazis. In the fictional world of Trek on the other hand there are a lot of folks who want the whole galaxy for themselves. Romulans, Klingons, Cardassians, the Dominion, even the Ferengi aspire to control everything and everyone. Yet peace, often a fragile one, with the Federation is possible and preferable from the view of the UFP. The reason should be obvious, there are so many of them! You cannot wage war against a dozens of species who have an agenda of total domination. It would be extremely bloody, extremely costly and sooner or later make you resemble your enemy more and more and the lines written in your constitution less and less. We saw what Federation officers have been willing to do during the Dominion War.
None of this doesn't imply that the peace treaty between the Federation and the Caradassians is perfect. The logic is probably a pretty cruel one, accept a few issues in the DMZ in order to prevent another war with millions of casualties. That's a natural problem of managing large political entity like the Federation and the Maquis had a point, they had to suffer such that other people did not have to.