Dukat's development was ruined but it was HIS choices that made it that way. And its true that sometimes people change but as Mr. Burns puts it, 'They can also bloody well change back,' and the essentials of Dukat and his history never changed. Dukat in my opinion got a free pass because Ziyal was such a sweet girl and when she died you feel bad for him and then some of the viewers care for her transfers.
Eddington's baiting of Sisko was massively entertaining, because it was clearly true. I'm with Eddington. But also Sisko had a point. 'Stop selling these people false hope...' but then Sisko is working for the organisation that sold their homes out from under them. Eddington has got my vote.
I confess I liked Eddington better than Dukat partly because of what you pointed out; both sides did stupid, irresponsible things. The Federation sold out it's own people in exchange for a quick peace with a treacherous opponent, and the settlers were foolish enough to trust the Cardassians.