Risen suggests a few reasons. First, he suggests it's a class thing. Americans are moving away from blue collar work and are no longer the type of people who "drink beer". I put the least stock in this idea, but I do think class consciousness is a component. What's more likely, though, is that people are beginning to feel like you don't have to be a snob to drink craft beer (or non-beer beverages, for that matter). Risen also cites "hipsters" who crave innovation and originality. I'm sure this has something to do with it - but I don't think the "hipster" label is necessarily appropriate for describing new beer preferences. To a large extent, I don't think it's hipsters breaking into beer consumption so much as the expansion of existing understandings of "authentic" beer. The most obvious example of this is the beer drinker known as the "hop-head", who enjoys a heavily hopped, very spicey/floral beer as opposed to a rounder, maltier beer. I enjoy hoppier beers relative to maltier beers myself, but some of these guys strike me as approaching beer drinking like a chili-cook off. It defeats the purpose for me. There are also people who like the extremely heavy, dark beers. While I can understand the hop-sensation, I just don't get this one. On a very cold winter day I can enjoy a heavy stout, but aside from that rare circumstance I'm absolutely not on board. Again, it seems to defeat the purpose for me. I don't drink beer for that chalky, barley-soup experience. The point I'm trying to make is that these aren't really "hipster" tastes or mentalities. These preferences come from people who have the opportunity (which they didn't always have in America) to really enjoy the essence of beer - to appreciate it on its own terms (despite the fact that I think they take it overboard sometimes). To avid drinkers of craft brews, this is authentic beer - it's not just the beer that their hipster bourgeoisie sensibilities can stomach.
What I find interesting about this is the extent to which we really have dueling authenticities in beer. My parents are local, and whenever Kate and I visit for a meal, I get the chance to drink something I never drink: a Budweiser or a Natural Light. That's the stuff my dad grew up with. That and similar brands were all there was for a long time. But the thing is, guys of his generation see that sort of stuff as authentic beer, and the newer stuff as "hipster", imposter beer. And they're aware of the trends too. The old stuff sells in the same aisles as the new stuff, after all. Whenever I come over my dad always has the same joke that is semi-teasing/semi-apologetic - he says "sorry Daniel, you're going to have to drink out of a can tonight - I don't have any bottled beer". A glass bottle is code for him for something "fancier" than what he drinks. I actually don't exclusively drink what you might call "craft beer". I get Yuengling (Risen goes over the Yuengling phenomenon), Coors, and Corona fairly regularly for budget reasons, but also because I genuinely enjoy the taste (of course my dad drinks the two beers that taste like carbonated water to me, and that I definitely don't pick up on my own).
I suppose my point is that trends in preferences are often more complicated than they appear. We usually interpret these changes as fads driven by what Risen calls "hipsters", but I'm not sure that's always the case. In a lot of ways, new preferences reflect a re-evaluation of older preferences and a genuine attempt to return to some sense of authenticity. This can result in older and newer generations critiquing each other and claiming that the other just "doesn't understand what real beer [or any other product] is." The reaction is understandable for both, but I think largely inaccurate.
I think you see this in wine too, which I'll briefly mention because the article does as well. I'm not by any means a wine or a beer connoisseur, but I suppose I'm an amateur connoisseur. One of my favorite movies is Bottle Shock, which tells the story of the 1976 blind tasting between French and California wines, where the upstart Californians demolished the French competition. To the French, the Californians were a joke. To the Californians, the French had lost the real beauty and purpose of wine making. Dueling authenticities. Kate and I mostly drink wine from Virginia wineries (it's not well advertised outside the area, but Virginia is home to about 250 wineries which have a comparative advantage in grapes like the Cabernet Franc and the Viognier, as well as less broadly known grapes like the Norton). We find that we can slip into this sort of us-vs.-them attitude too. California wines just seem so old and tired. Besides, you can't beat the authenticity of drinking a wine that was housed in a cellar we've walked in and made by people we've met and talked to on numerous occasions. I think the excitement for new endeavors is great, but I do regret this impulse sometimes. I really don't know California wines (much less European wines) as well as I should. Someday I tell myself I will - but for the time being I do enjoy my own preferences.
I'm not sure how to sum this up. I guess it's just an appeal to see things from multiple perspectives, particularly when we're talking about something as subjective as personal preferences. Understand the irony of assuming that your own view and your own preference for an item that has been around for millenia is somehow the "authentic" version of the item.
Probably also worth noting what I personally drink. I noted the more standard stuff I drink earlier. My favorite beer, which isn't being produced anymore, is New River Pale Ale. While I'm on discontinued brews, I also like Tupper's Hop Pocket Ale which has only recently been selling again. This is about as hoppy as I usually like it. Both of these are more or less local - I like to pick up local beer just like a I like local wine. In that vein, the brand I probably pick up most often is the Old Dominion Brewing Company, which has several good beers. These aren't as "hipster" as some craft brews come - fairly traditional (dare I say "authentic"?) styles. I also like Starr Hill Brewery, in Charlottesville, although probably not as much as Old Dominion. Clipper City Brewery in Baltimore has some really great stuff too. My favorite is the McHenry Lager, but they're probably best known for their "High Seas" series. Kate and I saw a presentation by the owner at a food and wine expo once, and he walked us through their beers. One of the neat things about Clipper City is that they produce a lot of different beers, and offer a nice progression from heavier to lighter beers and from maltier to hoppier beers, so that you can really figure out what you like. Other than those, I regularly buy Sam Adams (it's hard to beat the Boston Lager - it's a classic), I used to get Red Stripe a lot, Flying Dog, and Killians. Some day perhaps I'll share some of my wine favorites too.
I should note that a week or two ago when we were over at my parents, my dad had started branching out. On the advice of a friend, he had a Blue Moon (a Belgian style brewing company that makes a lot of wheat beers) when they were out to lunch one day and liked it. I occasionally like wheat beers, but not usually. Kind of an odd one to draw my dad's attention away from Budweiser and Natural Light. But that's the great thing about preferences - you don't have to explain or justify them. You just have to have them and act on them. He ended up getting a six pack and I drank Blue Moon that night.