I mean call me what you will but in my opinion, what makes a song memorable and a classic is a riff that you can immediately attribute to that song. Enter Sandman from metallica for example, or Toxicity from System of a Down, Scar Tissue by the Chili Peppers are all overt examples of where a catchy riff has played a huge part in making that song the way it is.
I mean think for example Black Sabbath - Iron Man! what is that song without that riff??
I was listening to the new chili peppers album and i couldn spot a single catchy riff, was listening to some tool songs my friend told me to download, no catchy riffs there either. It's just powerchords, or really fast solo's (even solo's are out!).
Are hard rock songs becoming way to simple and too unoriginal ? I hate to be stuck in the past but a catchy riff makes a classic in my mind and if hard rock songs are getting simpler will they end up as just one chord played over and over again whilst an emo singer passed off as a metal god scream about how crap his life is?