I Am has some pretty high notes, so that's probably the reason. And Hook Me Up was neither a single nor is it that much of a classic. I like it as well, but I can understand that it's not a regular. As with "surprises", if a classy song like "Blood On Blood" is a surprise nowadays, well...

As for I Am... Two words: Mediocre guitarwork. Yeah, it's got a nice chorus, fitting lyrics and all, but the solo and the fills really aren't pushing the edges at all...