WHY DO PEOPLE love wine bars so much? A single-beverage bar where the food is tiny and the tables smaller still is an arrangement whose appeal is a bit of a mystery to me. Yet I realize mine is a minority point of view, since the number of wine bars all over the world just keeps growing and growing.

When the wine-bar boom began about five years ago, I thought it was a trend that would eventually end. How big an audience could there be for establishments that specialized in small plates of cheese and wines by the ounce? I was sure that people would realize that a good glass was best savored by the bottle and not in a "flight." (A "flight" is a cute wine-bar name for tiny glasses of wine with a big price.) But clearly my powers of prognostication are flawed, as Americans' love of wine bars seems to be a long way from flaming out.

According to Stefan Mailvaganam, the wine-bar market will "only get bigger" in the coming years. Mr. Mailvaganam is a successful, serial wine-bar entrepreneur; he has opened three thriving New York wine bars in the past five years (Bar Veloce, Vanguard Wine Bar and Custom American Wine Bar) and is looking to add a fourth to his empire.

Mr. Mailvaganam believes wine bars fill an "untapped niche" for drinkers, especially budding young oenophiles. These vinous neophytes use wine bars in part to "transition into adulthood," said Mr. Mailvaganam, who characterizes his establishments as "adult coffee shops" that are thriving in this Internet-dating era.

Of course, a drink at a wine bar costs more than a latte at Starbucks; the average glass of wine at one of his establishments costs $10-$12. And at some wine bars, it's a glass of wine that's not exactly a discovery; I've been to wine bars where the by-the-glass offerings are wines you might see on a shelf at a grocery store. When I mentioned this to Mr. Mailvaganam, he acknowledged it was something he worked hard to avoid. His by-the-glass offerings are mix of the familiar (Pine Ridge Chenin Blanc) and the more obscure (Crémant de Limoux).