Why do those elitist millennials hate Big Beer?

Sleek black-and-white bottle design. Strong, lingering taste. A boozy alcoholic punch.

None of these scream Budweiser (Sao Paulo Stock Exchange: ABEV-BR), Miller or Coors, the three big brands in American beer. Yet in the past few years, all three have introduced new product lines reminiscent of increasingly popular craft beer and even hard liquor. Brands like Bud Light Platinum, Budweiser Black Crown and Miller Fortune veer sharply away from the formulas that produced America's most popular beers.

What's behind the pint-size pivot?

American millennials aren't drinking what their parents were. Young drinkers are quickly abandoning the major domestic standbys for import and craft beer.

Over the past five years, Budweiser has seen a 28 percent decrease in domestic sales volume, while Bud Light-still the most popular beer in America-has seen its sales go down 10 percent, according to Beer Marketer's Insights. The light beer market as a whole, for that matter, is struggling: Since its sales peaked in 2008, the domestic light beer segment has sold 8.3 million fewer barrels in the United States, a decline of 8 percent.

Meanwhile, craft beer sales have been steadily rising. Shipments sold of craft beer rose 13 percent in 2010, 14.5 percent in 2011, 14 percent in 2012 and another 14 percent in 2013. Overall, craft had a 7.8 percent share of the domestic market in 2013.

These trends seem to have been driven by the buying habits of young Americans.

"The 21- to 27-[year-old] beer drinker is, and always has been, the critical demographic, and they're shifting towards craft," said Ben Steinman, president of Beer Marketer's Insights. "I think that there's a move towards innovation, flavor, variety, and all of those spell craft," Steinman said.

The drive towards craft beer may be driven by the simplest of factors: taste. Of consumers who are choosing to drink fewer mass-market light-beer brands, 27 percent said the primary reason is "getting tired of the taste," while another 21 percent "were consuming more types of other beer," according to a Consumer Edge survey.

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Among drinkers age 21 to 27, the "getting tired of the taste" answer jumped to 40 percent.

"They're not as loyal as their parents were," said Joe Thompson, president of the Independent Beverage Group. "We came from an age of megabeers. And now the people that made the megabeers famous, their children are the millennials. And they don't want to drink what their parents did."

From 1992 to 1994, 71 percent of 18- to 29-year-olds chose beer as their favorite alcoholic drink, according to Gallup. That rate dropped to 41 percent in 2013; for all adults, only 36 percent picked beer.

In 2014, those numbers inched up slightly-48 percent of 18 to 34 year-olds chose beer as their favorite alcoholic beverage, compared to 41 percent of all adults.

An increasing preference for beer does not necessarily mean more sales, especially when craft beer is involved. "As young drinkers switch from a Miller Lite to a craft, they'll drink one or two crafts when they used to drink three or four Miller Lites," Thompson said.

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That's not only because craft beer tends to be more expensive. It also often has a higher alcohol content. Whereas Bud and Coors Light both have an alcohol by volume (ABV) of 4.2 percent, those of craft beers are usually significantly higher. The average American Pale Ale (APA) has an ABV of 5.5 percent, while the average American India Pale Ale (IPA) has an ABV of 6.7 percent.

In short, the millennial drinker may have realized that they can get the same buzz from two craft beers as from three lights and get a better-tasting beer in the process.

The big brewers haven't been ignoring these trends, having tried to brew up solutions for some time already.

Both MillerCoors and Anheuser-Busch have attempted a shift towards higher-margin "premium" beers and drinks that carry their flagship beers' names. Anheuser-Busch, for instance, recently introduced Budweiser Black Crown and Bud Light Platinum, both at a 6 percent ABV, which sell at a price premium of 10-15 percent. The Bud Light Lime-A-Rita and Straw-Ber-Rita, malt beverages with an 8 percent ABV, sell at a premium of 60 percent to 70 percent.

In early 2014, MillerCoors brought out Miller Fortune at a 6.9 percent ABV, a direct competitor to Black Crown. Its recent branding and commercials, set in gritty urban environments, are similar to those of advertising for spirits, which Thompson claimed "have done a great job of going after young adults."

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These drinks are targeted directly at consumers who may otherwise have eschewed the mass-market beers; an Anheuser-Busch InBev report stated quite plainly that these innovations "are being priced at a premium, while bringing new drinkers into the category."

But despite their high-energy rollout campaigns, the new premium brands have had a decidedly mixed record of success. Though sales figures for Miller Fortune have not been released, the ad agency that produced the aforementioned campaign was fired in April only months after the brand was released.

In its first quarter 2014 results, Anheuser-Busch InBev noted that a company-wide 0.4 percent market share decline was due primarily to Budweiser Black Crown, not exactly a ringing endorsement. And after a strong 2012 launch, Bud Light Platinum's sales dropped in the second quarter of 2013 and plateaued thereafter.

The big brewers have also tried to cultivate craft beers of their own. Though a craft brewer is defined to produce under 6 million barrels of beer per year, according to the Brewers Association, large companies have tried to take a gulp of the growing craft segment by buying up smaller beers or introducing their own.

Shock Top, controversially ranked by Consumer Reports as among the top craft beers-you would be right to ask who goes to Consumer Reports for their beer research-is an Anheuser-Busch product, as is Goose Island Brewery. Blue Moon, purportedly America's most popular beer, and Leinenkugel are MillerCoors brands .

Still, less than 25 percent of craft breweries are owned or controlled by an industry member that is not a craft brewer. The big brands have focused more on importing popular foreign beers in an effort to combat falling sales of their traditional standbys. AB InBev, the world's largest brewer, brings to the American market Corona (Mexico), Stella Artois (Belgium) and Beck's (Germany); SABMiller (London Stock Exchange: SAB-GB), the second largest, imports Pilsner Urquell (Czech Republic) and Peroni (Italy).

The big brewers are still on top and are likely to stay there for the foreseeable future. "They're declining, but they're still huge," Steinman said. "Demise is too strong a word."

Either way, the days of an American beer market utterly dominated by Miller, Coors and Budweiser seem to be over. And you can blame it, at least in part, on the refined taste buds of millennials.

-By Nicholas Duva, special to CNBC.com