Maybe pop culture doesn't exist then.
Though it depends how one defines it. If it's media-driven attitudes and memes, then the media in 24th century Earth or the Federation in general may be very different from today.
Also, as the Federation is a multi-species union, not all cultures may even have media (at least as we know it or would recognise it).
Pop culture (or mass communication) today is economically and politically driven. That was true in ancient times, with theocratic and monarchial control over mass communication and ceremony, that is so in today's corporate-state society. The system only promotes itself through its communicative means. In Roddenberry's future those factors are not supposed to exists anylonger, so pop culture/consumer society (at least as we know it) shouldn't exist either. I think Roddenberry was envisioning a more creative rather than consumerist society based on mutual support and equality rather than competition.
"A culture now wholly commodity was bound to become the star commodity of the society of the spectacle. Clark Kerr, an ideologue at the cutting edge of this trend, reckons that the whole complex system of production, distribution and consumption of knowledge is already equivalent to 29 percent of the annual gross national product of the United States, and he predicts that in the second half of this century culture will become the driving force of the American economy, so assuming the role of the automobile industry in the first half, or that of the railroads in the late 19th century." -- Debord.
Looking around the country and the world it is the economies dominant face.