When you call them colonies, I get the impression most people think they just landed down there yesterday. That's not really the case. They had been there for at least one generation as Voyager mentions some of their Maquis having been born in what is the DMZ.
Anyone there would have every right to be angry to have their home ceded to an aggressive expansionalist empire in the attempt of appeasement when their behavior had already showed they were not at all interested in peace.