In actual history, this only happened when the victors (by peace treaty or similar means, not complete victory/occupation) were foolish enough to let a developed country all but unsupervised
The key factor there would appear to be whether the defeated country was annexed or not.
In (European) history, annexation of defeated enemies has gone in and out of fashion - and in the 20th century was very much out of fashion, it being quite unthinkable for France to annex Germany, say. Even minor border provinces or distant colonial holdings were rather declared "mandates" or "neutral zones" or "joint control regions" or whatnot. This meant that industries and national feelings indeed could rebound even after a decisive defeat in the battlefield.
Nothing of the sort was possible e.g. for Poland on all those occasions where the country or nation itself ceased to be in terms of geography. Foreign, split rule and the existence of internal borders would quite physically prevent industrial recovery or the assembling of unifying political parties or movements.
The Cardassian Union would be hacked to pieces by the very fact that its defeat apparently consisted of the gradual conquest of its outer holdings in a great inward push (and never mind that the decisive strike was one of the Washington vs. Richmond sort, a short hop made possible by shifts in the overall balance of power rather than in locally relevant military factors). On the other hand, Cardassia itself might well remain undivided and the vast majority of Cardassian people untouched by occupation or other rule by the victors. Their traumatizing or depowering experiences would come from their wartime alliance gone sour, which might in fact be conductive of national pride.
As for the other POV, that of the victors... Klingons probably wouldn't be all that hot about weakening their enemy beyond a certain point. They prefer strong opponents, especially when those have been decisively defeated (compare to the idolization of Rommel or Napoleon in the British tradition). From which it follows that Romulans would love
to give Klingons exactly what they want! And the UFP would want to see Cardassia rise again for humanitarian reasons. With such agendas at play, it is far from implausible that everybody would get way more than they bargained for.