AC/DC have a huge canon of well-known, beloved songs all more than worthy of their popularity. Despite the fact that they're overplayed by classic rock radio repeatedly, I never get tired of "Highway to Hell," "You Shook Me All Night Long" or "Back in Black." They're that good. Casual fans without an appetite for multiple purchases seem to stick with Back in Black and consider their AC/DC collection complete. Or maybe they don't even know any better. When I was sharing my plans with a co-worker to see the band on the Black Ice tour she replied, "AC/DC - oh, yeah! I have their album!" And while any band in the world would likely sell their soul for a record half as good and successful as Back in Black, any true-blue AC/DC fan will tell you that there's a lot more to enjoy if you dig a little deeper.
AC/DC have long avoided both iTunes and assembly of a hits collection (though their two soundtrack albums serve as piecemeal versions of the latter), preferring their albums to be enjoyed just as that - full-length presentations of songs. I admire them for sticking to their guns. They've been accused of making the same album over and over but when they're filled with songs like "Kicked in the Teeth" who would want anything different?