Anyone else catch that VH1 Honors thing? I began watching just as Godsmack started their Judas Priest medely. One thing that comes to mind is that: A large portion of newer bands can't play live anywhere near as well as the old ones. The bands that grow up on ProTools and autotune simply do not cut it as well as the ones that had to perform instead of hire an expensive producer to slice n dice their performances into a radio-friendly mix.
While I'm not really a fan of this band: The Def Leppard cover of T-Rex (with Brian May guesting on guitar) was pretty top notch. The All American Rejects cover of Def Leppard was pretty dismal, mostly becuase of a weak vocal performance.