I'm really picky when it comes to what I read. I'm a snob, because I've spent the past 16 years reading every and anything that passed through my hands no matter how poorly written and juvenile it was. I loved Twilight when I was in sixth grade, Jesus. But the older I grow--and the more well-read---the more liable I am to kick out a book by its cover alone. To be fair, though....
The covers have been pretty telling.
Look closely. See any books that have been recently noted or significant in our culture? See any that don't look like they could have a common plot line? That's because there aren't.
The problem, as with any sub-culture, is that it's all about marketing. Publishing houses buys what sells, and little to nothing else. Remember that huge explosion of the vampire/paranormal romance genre after Twilight? How after The Hunger Games blew through the ceiling, all sorts of teen survival/post-apocalyptic series popped up?
As creatures of habit, when we find something we like, we prefer to stick with it then venture out and find other novels when we already have a set taste. Movie studios, TV producers, the Kardashians, Publishing houses and especially fast food chain stores know this. So the same novel gets mass-produced ten more times with minor changes in names and setting, but quintessentially the same where it matters most. God, they can't even change the cover, either. It's like the call sign.
Because a lot of these books are just...bad. Besides the whole being unoriginal as dirt thing, they're poorly written in terms of style and narrative, have weak story structure and character arcs, and tend to have lots of meaningless details that don't build character or move the plot. It hurts my brain. Like eating fruit snacks and McDonalds every day for your whole life, it just clogs the vital parts of your brain (like creativity, problem-solving, self-evaluation, moral and ethical considerations) turning it into mush. You cannot transcend what you do not know, and many of these books aren't worth knowing.
The reason Harry Potter and The Hunger Games were so popular was because they were, in contemporary literature, novel. They had interesting characters, an interesting setting for the drama to play out, and an unusual plot. While they may have succeeded from the genres before them (Think Lord of the Flies to The Hunger Games), they came together well and weren't terribly written. And they weren't like everything else that was printing at the time.
Because as much people like their easy-pleasures, they love new experiences more. What's more refreshing that an original book?