If someone went back in time to AD 1273, looked up Friar Thomas Aquinas, and told him all about life in these United States in AD 2005, the good friar might well reply, "Yes, I wrote a book about that."
TSO calls attention to a couple of posts at Crux Magazine. The first one suggests that "we have reached the end of not only shame but the private experience thereof." The second makes "the observation that illegitimate sex also appears to coincide with a desire to eat."
In the Summa Theologiae, St. Thomas links gluttony and lust (along with drunkenness) as vices opposed to [the subjective parts of] the virtue of temperance. Little surprise, then, that the intemperate person should be both glutton and lecher, particularly in a society with an overabundance of food and fornication.
Furthermore, shamefacedness is listed as an integral part of temperance (though not, properly speaking, a virtue, since avoiding shame is not particularly difficult for virtuous people). Shamefacedness is not a notable feature of American popular culture. St. Thomas identifies three kinds of people who lack shame: "those who are steeped in sin... the old and the virtuous." Which kind of person American popular culture is by and for is left as an exercise to the reader.
(Sorry, I just gotta like his throwing "the old" in there; his reasoning is that their appetite for intemperance is easily curbed.)
So St. Thomas would likely regard this culture as marked by intemperance. Any particular reason we might be particularly intemperate? Perhaps there is:
...sins of intemperance are said to be childish. For the sin of intemperance is one of unchecked concupiscence, which is likened to a child in three ways.
The three ways are in acting on unreasonable desires; in becoming more self-willed if given free rein; and in the remedy, which is restraint.
A society of childish persons, of persons who don't grow up, is an intemperate society.