The Brobdingnagians are the epitome of moral giants. Physically huge — 60 feet tall — their moral stature is also gigantic. Brobdingnag is a practical, moral utopia. Among the Brobdingnagians, there is goodwill and calm virtue. Their laws encourage charity. Yet they are, underneath, just men who labor under every disadvantage to which man is heir. They are physically ugly when magnified, but they are morally beautiful. We cannot reject them simply because Gulliver describes them as physically gross. If we reject them, we become even more conscious of an ordinary person's verminous morality.
Set against the moral background of Brobdingnag and in comparison to the Brobdingnagians, Gulliver's "ordinariness" exposes many of its faults. Gulliver is revealed to be a very proud man and one who accepts the madness and malice of European politics, parties, and society as natural. What's more, he even lies to conceal what is despicable about them. The Brobdingnagian king, however, is not fooled by Gulliver. The English, he says, are "odious vermin."
Nevertheless, the Brobdingnagians are not without their flaws. Unlike Gulliver, who always considered the Lilliputians to be miniature men, the Brobdingnagians cannot think of Gulliver as a miniature Brobdingnagian. Even the King, who is sincerely fond of Gulliver, cannot view him as anything except an entertaining, albeit sly little fellow, one who is not to be trusted. The maids of honor in the Brobdingnagian court treat Gulliver as a plaything. To them, he is a toy, not a man, so they undress in front of him without a thought of modesty, and they titillate themselves with his naked body. Still, this "abuse" of Gulliver — denying his humanity and his man-hood — is done for amusement, not out of malice. Although they are not perfect, the Brobdingnagians are consistently moral. Only children and the deformed are intentionally evil.
In short, Swift praises the Brobdingnagians, but he does not intend for us to think that they are perfect humans. They are superhumans, bound to us by flesh and blood, just bigger morally than we are. Their virtues are not impossible for us to attain, but because it takes so much maturing to reach the stature of a moral giant, few humans achieve it.