As I suggested in the other thread, the Pact was not meant to be an alliance of "villains" -- it was more about creating an opportunity to flesh out a number of background alien races that had not been given much development in previous shows or novels. It had a couple of major races, the Romulans and Tholians, to anchor it, but there was still very little known about the Gorn, Breen, and Tzenkethi -- and the Kinshaya were a totally obscure race that had only been mentioned in passing in a couple of novels.
The telling part is the inclusion of the Gorn, who have usually been portrayed as having friendly relations with the Federation in the wake of that initial misunderstanding in "Arena." Indeed, in the novel continuity, which incorporates the Wildstorm graphic novel The Gorn Crisis, the Gorn ruling caste actually owes its continued survival to Picard and Data, who helped them defeat a coup. The fact that they were included in the Pact shows that it's not about being an enemy of the Federation, just about being an alternative. And the Kinshaya have no history of interaction with the Federation one way or the other; their historical enmity is with the Klingons, and a case can be made that they're more the victims there than the aggressors. They really have no interest in clashing with the Federation but just want to be left alone. To a large extent, the Pact is just about giving the races of the quadrant an alternative to being dominated by the Federation as a lone superpower. They don't want to invade or conquer or destroy us, they just want to be left alone. Granted, the Tholians and Breen have more aggressive designs than the rest, but as the Vanguard series makes clear, the Tholians see their actions as self-defense, or as retaliation for the Federation's past abuses.
And as the TP novels progress, you'll find that the Romulans end up going in a rather unexpected direction that makes it even harder to reduce the Pact to a "league of villains."
In any case, as I said in the other thread, the biggest mistake is to talk about the entire Pact as a monolithic "they." It's six different "they"s (possibly more, since each one has different internal factions) that are as likely to be at odds with one another as with the Federation or anyone else.