Chuck Klosterman wrote a thoughtful article yesterday where he attempted to dissect why people hate bands like Nickelback, while attending a Nickelback and Creed show in the same evening. The article is definitely worth a read if you're interested in music from both a technical and sociological standpoint and, for the record, Chuck Klosterman remains one of the top 3 people in the world I'd love to share a meal with (though I suppose that's irrelevant). Anyway, I figured I'd throw in my two cents on the subject because I believe the answer is kind of simple.
People hate Nickelback because they are the Walmart of Rock and Roll.
Before I explain my theory, I first must say I do not hate Nickelback. In fact, I don't really have much of an opinion on them, period. I have their song "Photograph" on my iPhone, and don't cringe when it comes on, and I may have another of their tunes downloaded and don't even know. So there, I'm not speaking from a position of bias. Now that we got that out of the way...
People use music preference to express individualism. It's why many blast their music from car windows, and why band shirts are popular. These shirts differ from, for example, t-shirts featuring your favorite football team because those are supporting a community that is formed in the name of good-natured competition. It's to signify you belong to a club. A t-shirt featuring your favorite band is an expression of what kind of person you are, or more specifically, how you like to be seen. If you see someone wearing an old Metallica shirt, your mind automatically forms an outline of what kind of person that guy is. Same with an old Nirvana, Sonic Youth, or Pavement t-shirt. Those people directly involve themselves in the rock and roll subculture. But someone who wears a Nickelback t-shirt? Doesn't really say anything. But to rock and roll fans, it's almost like a slap in the face, and, if this were the 90's, the word "poser" would come to mind.
As Klosterman mentioned in the article, Nickelback's head man, Chad Kroeger, seems to have studied the elements to a hit song, and then created many Frankenbabies to sell the perfect, sellable record. Whether that's true or not, there's nothing that feels grass roots about the rise of Nickelback, but instead they appear more like a band that rode the coattails of their predecessors, or more aptly, a barnacle.
But even if the above is true, the question of, "why do people hate them" remains. Rock and roll is territorial. Whether you like indie rock, classic rock, "alternative rock," or if this were the 1990's "grunge rock," a fan would double down on their explanation to why a certain band was good because, as mentioned, they've mixed their self identity with the quality of the music. They might wax poetically about original lyrics, sounds, or they may mention the chances the band took in their pursuit of good music. Nickelback doesn't try to be original, therefore, they never gained that coveted audience that views themselves through a rock and roll prism. The only audience they earned is the top 40 audience, which is vast and great for cash, but bad for "legacy" (for lack of a better term). You won't find many Nickelback fans that will strongly come to their defense because people who listen to top-40 are generally passive music listeners. If you ask a Nickelback fan why they like their music, you probably won't get an answer that's anymore revealing than a shrug.
So, the only way to express individualism through a band like Nickelback is to claim to hate them, because a vote against Nickelback is a vote against conformity. And since rock and roll was built on the back of rebellion, bands like Nickelback become to whipping boy for people who want to show their individuality by suggesting they are "above" a band that chooses perceived conventions over "originality."
But hey, bands like Nickelback are generally harmless, always on the radio, and we'll continue to passively listen to them and complain when one of their songs gets stuck in our head. Sort of like when you need toiletries and the easiest place to get them is Walmart. We'll bitch and shop there anyway because it's convenient and there.