If we take Eddington at his word why does the Federation want the Cardassians to join?

Thanks u/historydave for getting me to think about this as much as I did.

The Federation has just gotten done fighting a 19 year-long war against the Cardassian Union, a war in which the Federation ceded some of its colonies to the Cardassian Union for peace, it has moved into the formally Cardassian occupied Bajor system with the intention of helping the Bajorans rebuild and eventually join the Federation. The Central Command has recently been deposed and power assumed by the Detapa Council although its military is lead by Gul Dukat former prefect of Bajor. Currently, the Cardassians are at war with the Klingon Empire (a former Federation ally) and are receiving economic aid and military support from the Federation.

It is at this point Eddington makes his claim that (to paraphrase) the Federation is providing the Cardassian Union aid is so that eventually they will join the Federation, however, why does the Federation want them to join and how long as this been their goal.

I'm going to divide this into two scenarios and explore each,

Scenario A: This has been the Federation's goal for a while.

There are a few possibilities here, first, the Federation feels a moral responsibility to remove the Fascist police state the Cardassians live under and getting them to join the Federation might remove the need for such a state to exist. However, if that's the goal you had a war that would have justified going in and ending such a state since it was a direct threat to Federation colonies. Does the Prime Directive cover not interfering with the internal matters of a nation actively at war with you?

The Federation needs something. Do the Cardassians posses something the UFP needs. We know the Cardassians are resource-poor which is why they annexed Bajor but do they have something else; like do they not have the material needed for starship construction but posses lots of dilithium? In such a case wouldn't just making them a trading partner work? It could be that the Federation populous wouldn't support trade with a state like the Cardassian Union due to the Cardassians Fascist politics; therefore they need to get them to join the Federation to end those policies to open trade. However the fact that they would be willing to trade if the Cardassians reformed could be the economic pressure needed for the Detapa Council to reign in the Central Command an Obsidian Order- basically if I the Cardassian on the street knows we could get the resources Cardassia needs to build itself up from the Federation through peaceful means why do I need to support this war machine whose job is to play conquistador to get those resources.

The Cardassian's militarism isn't even that old that it's simply become “the way of things”, it might only be 60 or so years old as the “First Republic” existed in the 23rd century and even had good enough relations with the Federation to award Starfleet Captain Christopher Pike two awards! Another possibility is that the Federation needs labor. As much as people don't like to talk about it (at least in the mid-to-late 23rd century) the Federation used prison labor to augment its dilithium mining industry, by the late 24th century they were using conscripted holographic AI for mining; does the post-scarcity utopia have a problem getting people to volunteer for hazardous jobs like dilithium mining and the Cardassian Union has a large and willing workforce? An extension to 'the Federation needs something' could be the Federation needs markets. But the Federation economy doesn't seem dependent on exports.

Next possibility the Federation is playing “The Great Game”, and simply wants to deny Cardassia as an ally to some other power? If for example if the Romulans ally with the Cardassians it could counter the Federation-Klingon alliance; given the Cardassians and Romulans don't share a border (Dominion ships attacking from Romulan space was because the Dominion had advanced deep in to the Federation's northern territory as I've shown before on Daystrom) so they wouldn't have the issue of both claiming the same systems and be unwilling to help each other- basically work together to divide the Federation and the Klingon Empire between them. Could it be that by gaining membership of the Cardassians it removes a power that might form a power bloc that might oppose the Federation? The Cardassian Union is the 4th largest power in the Quadrant and it is located near the Tzenkethi Coalition, Talarian Republic, Ferengi Alliance, Breen Confederacy, and to some extent the Tholian Assembly plus it has good relations with the neutral systems that exist between the UFP and its border to the galactic north-east (the Xepolites, Klaestrons etc). That could form a potentially powerful alliance (like the Typhon Pact of beta canon) of its own if they all feel the common threat of the combined Federation-Klingon alliance is a danger to their sovereignty.

Finally, the Federation is seeking hegemony in the quadrant. All must join the Federation eventually and discover the true freedom that comes with the Federation way of life. In such a case Eddington was right, the Federation is just the Borg with better PR.

Scenario B: This is a recent development.

They only want Cardassian involvement in the Federation because the Klingons have broken their Alliance. I find this a kind of 'iffy' idea, if an alliance was so important then why did the Federation not heed the Klingon call to arms in 'The Way of the Warrior'? Its possible Federation president Jaresh-Inyo's pacifism made him choose to not aid the Klingons but even then if an alliance was that important wouldn't the Federation Council moved to stop his decision? Either a call for a vote of no confidence or impeachment (depending on how the Federation system works) or, as happened later due to his policy decisions a Starfleet lead coup. Is it so impossible to prevent or undo Jaresh-Inyo's decision not to aid the Klingons that aiding the Cardassians and entering a de facto war with the Klingon Empire on their behalf is the only solution?

Democracy has broken out so they must want to join the Federation. Yes, the military has been overthrown but does that mean they automatically want to be part of the Federation? Plus this is the same civilian government the old military reported to anyways so are they that different? Is just them growing a backbone and slapping down the Central Command enough for the Federation to welcome them with open arms; they have selected as the head of their new military none other than Gul Dukat so how different could it be.

Its the Dominion working the split the Federation. Could Changelings have replaced enough Federation politicians to influence the Federation into helping a former enemy (that is downright hated by some in Starfleet) to get the Federation to fracture? While possible it doesn't explain the questionable concessions to the Cardassians in the peace of 2367. It also wouldn't explain how such a questionable political position would allow such politicians to remain in office unless its supported by a sizable faction of the Federation population (a Changeling infiltrator is all well and good but if the person they are impersonating gets voted out of office it doesn't matter)- which brings us back to why would they want such a thing; a part of the Federation population formed its own militia lead by former Starfleet officers to resist by arms the terms of the peace of 2367. Is it a question of 'this is the only way we can get the territory back', but then why give it up to begin with? Was the Federation so weak it couldn't hold it against the Cardassians? In other words is the Federation is a paper tiger, at least back in the early 24th century (Cartwright and his supports warned about the dangers of mothballing Starfleet). Or was the Federation Council or the Federation citizenry unwilling to support a war to defend its own planets? If its a question of we'll give you the territory now but we'll get you to agree to annexation later to get it back we're back to Federation hegemony.

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So what is it?

Am I missing a potential reason?

Does one of my reasons make sense?