As far as I recall the only good thing that the Cardassians did was get rid of a caste system...though they replaced it with a system of wholesale discrimination, all Bajorans are scum!, which they believed was completely cromulent
You have to wonder what would have happened to Bajor if Sisko never found the wormhole. Given how fractured and that thanks to the Cardassians they were stuck in a cycle of violence that the government would have collapsed and the various factions would have gone to war against each other. The Bajoran civilisation that lasted over 500,000 years might have been destroyed in just a year of "freedom". So I think that all the Cardassians did was tear the Bajoran civilisation to the ground and leave it to die.