What gets me is the insinuation that the Federation wanting others to join is SHOCKING AND CORRUPT AND TERRIBLE. ...it's a freaking alliance of worlds. The more members you have, the better the position of the Federation as a whole is, and it's mutually beneficial both for the whole (since that's another source of innovation, thinkers, resources, etc.) and for the world in question (more support, inclusion in beneficial treaties, etc.). I never understood why being nice to worlds in hopes of eventual membership is somehow underhanded and dastardly. Isn't that generally a good way generate interest in membership? By showing benefits and being a trustworthy ally?
And for that matter, when does the Federation EVER, in all of filmed canon Star Trek, PUSH ITSELF on other worlds? The only times we really see prospective worlds (that I can think of! feel free to correct me if I'm missing something) are in the TNG episode "First Contact" where THEY AGREE TO LEAVE FOREVER at the aliens' request, and with Bajor, who wanted the Federation to oversee the fallout from the occupation.
The Federation once described by the Klingons as a 'homo sapiens only club' is not an alliance of worlds but a Federation of worlds. Which implies some sort of top down rule. a lot of the smaller worlds could be seriously impacted by membership in a negative way by policies they dont agree with.
If by "the Klingons" you mean ONE Klingon who didn't trust the Federation partly due to years of hostility between them and her people, then SHE did describe them as such. And yeah, what an objective view of the Federation to take completely over what we've actually been shown of it.