Pop is not bad kid ,There are more pop acts than the disney channel acts and that fag of justin bieber . This covers are not bad but they're nothing special .At least all of the versions that you put on this list are so much better than the ones present on lame cds like pop goes punk.
I'm guessing you're fairly young (in your 20's) or haven't been listening to metal too long. This is not meant as an insult - just an observation since you left out a buttload of outstanding covers done prior to 1990. Here's a handful off the top of my head.
Astronomy Domine (Floyd covered by Voivod)
Diamonds and Rust (Joan Baez covered by Judas Priest)
Green Manalishi (Fleetwood Mac also covered by Priest)
Got the Time (Joe Jackson covered by Anthrax)
Mexican Radio (yes I'm serious) ( Wall of Voodoo covered by Celtic Frost)
Gonna Get Close to Youi (Lisa Dalbello covered by Queensryche)