It’s been roughly three decades since penetration reached 30 percent of U.S. homes, making it a viable advertising medium. Along with improved satellite transmission, this triggered the explosive development of specialized channels such as ESPN, MTV and CNN, eventually leading to more than a hundred others.

Right from the start it was clear that the best way to organize so many channels was in tiers, with package pricing. True, more viewers cared about major outlets, like USA Network, than lesser-known channels of the era, such as MSN (Modern Satellite Network). Cable operators paid fees to carry the popular channels, while usually getting the smaller ones for free.

A lot has changed over the years, but the formula remains pretty much the same. Today, for example, cable operators pay to carry CNN, and they get its sister channel, HLN, as part of the deal—which is essentially how it’s marketed to the public. A subscriber who feels cheated because he never watches HLN is as mistaken as someone who believes he should pay less for a newspaper because he never reads the comics.

Increasingly we hear about consumers like Vikas Bajaj, who wrote in the New York Times that he’s thinking of “cutting the cord” with cable. He mentioned a few shows he’ll miss, such as the AMC drama “Mad Men,” which he now plans to purchase for $22.95 per 12-episode season from iTunes. To my thinking, that’s a bad deal. My local cable company charges $34.95 a month for AMC, plus 59 other channels.

But there’s a bigger societal issue here. Part of the benefit—indeed, the pleasure—of flipping channels, surfing the Web or turning pages of a newspaper, is that it helps expose us to more than what we already know we’re interested in. For instance, I had never watched a show on Oprah Winfrey’s channel, OWN, until recently when I happened to see Ms. Winfrey doing a fascinating tribute to her close friend Roger Ebert, the film critic who had just died.

So, I’d ask Mr. Bajaj, how did you come to realize you enjoyed “Mad Men” until you had a chance to watch it? How will you know when the next series with similar appeal comes along if your cord is cut?

The great irony of the digital age is that the wider our options, the more narrow our focus.

I’ve got no particular fondness for the cable-TV industry, so I don’t care if the day comes when it is vanquished by superior Internet- or satellite-delivered technology. But I continue to covet my access to a wide variety of entertainment and information options, despite knowing I may never get to sample it all. That’s not a bad deal; it’s the essence of what our digital experience should be about.

When specialized cable channels emerged three decades ago, the industry labeled the new process “narrowcasting.” No one ever imagined that this horizon-expanding opportunity would someday lead viewers to become so narrow-minded.

(c) Peter Funt. This column was originally distributed by the Cagle Syndicate.