As for Metallica supporting other bands. Didn't James recommend The New Order when it came out (there was a sticker with his approval on the album I think)? Kirk and Rob always show some love for DA (and let them play a couple of gigs with them). They invited Laaz Rockit to open for them at the anniversary concerts. Not that they couldn't do more, but it's certainly not their obligation. Bands compete with one another (do you see Exodus supporting Testament were they the bigger band?). Anyway, the guys in the band probably don't have much say as to whom to take on a tour, it's all business (I'm guessing one has to put big money on the table to get the spot). Not to mention some of them have pretty much lost contact with anything metal really.