Hmm, not sure, I just saw Dickinson say that a in a recent interview I read somewhere (and actually it's pretty relevant the point Mark made about changing up the setlist when it comes to older songs). Bruce basically said the band wouldn't really want to go back and re-learn some of the older songs that haven't been played live in years or never because that would entail looking back and focusing on what's been rather than focusing on what's now. Hence the classic songs played live are for the most part the same old, same old.