Dude, they have just played Embody the Invisible during the last 4-5 years or so basically, not on this tour though. Episode 666 they played last I think 2010 or something. Food for the Gods was a long time ago though. They've played The Hive and especially in 2008 they played a bunch of older tracks. I think more than some of the songs they feel won't work good, and some others that they've played before they don't feel they get a good enough reponse from it.
So, it's not true that thay cannot play the old songs without doing justice to them.